bluuebunny/crossref_metadata_2025 huggingface dataset:
Screening for leukemia- and clone-specific markers at birth in children with T-cell precursor ALL suggests a predominantly postnatal origin
Authors: Fischer Susanna , Mann Georg , Konrad Marianne , Metzler Markus , Ebetsberger Georg , Jones Neil , Nadel Bertrand , Bodamer Olaf , Haas Oskar A. , Schmitt Klaus , Panzer-Grümayer E. Renate
Published: June 2007

Childhood T-cell precursor acute lymphoblastic leukemia (TCP ALL) is an aggressive disease with a presumably short latency that differs in many biologic respects from B-cell precursor (BCP) ALL. We therefore addressed the issue of in utero origin of this particular type of leukemia by tracing oncogenic mutations and clone-specific molecular markers back to birth. These markers included various first- and second-hit genetic alterations (TCRD-LMO2 breakpoint regions, n = 2; TAL1 deletions, n = 3; Notch1 mutations, n = 1) and nononcogenic T-cell receptor rearrangements (n = 13) that were derived from leukemias of 16 children who were 1.5 to 11.2 years old at diagnosis of leukemia. Despite highly sensitive polymerase chain reaction (PCR) approaches (1 cell with a specific marker among 100 000 normal cells), we identified the leukemic clone in the neonatal blood spots in only 1 young child. These data suggest that in contrast to BCP ALL most TCP ALL cases are initiated after birth.
Impact of Adoption of Chemoradiotherapy on the Outcome of Cervical Cancer in Ontario: Results of a Population-Based Cohort Study
Authors: Pearcey Robert , Miao Qun , Kong Weidong , Zhang-Salomons Jina , Mackillop William J.
Published: June 2007

Purpose

To describe the adoption of concurrent cisplatin-based chemoradiotherapy (C-CRT), and to evaluate its impact on the outcome of cervical cancer in Ontario.

Methods

We used a population-based cancer registry to identify the 4,069 patients with invasive carcinoma of the cervix diagnosed in Ontario between 1992 and 2001. We linked electronic records of treatment to the registry. We described time trends in the use of C-CRT, and we compared survival before and after widespread adoption of C-CRT.

Results

Over the study period, the proportion of patients treated with primary radical radiotherapy (RT) remained constant at approximately 42%. Between 1992 and 1998, less than 10% of RT cases received chemotherapy. Early in 1999, there was rapid adoption of C-CRT. Between 1999 and 2001, more than 60% of RT cases received C-CRT. There was a contemporaneous increase in overall 3-year survival from 71.1% in the 1995 to 1998 cohort to 75.9% in the 1999 to 2001 cohort (P = .03). There was no change in survival in patients treated with surgery alone. However, there was a significant increase in 3-year survival from 58.6% in the 1995 to 1998 cohort to 69.8% in the 1999 to 2001 cohort (P < .01) in the subpopulation of patients treated with primary RT ± chemotherapy.

Conclusion

The adoption of C-CRT was associated with a significant improvement in overall survival of cervical cancer at the population level. The magnitude of the benefit of C-CRT in the general population was consistent with the results of the relevant clinical trials.
Editorial
Authors: Nuijten Monique
Published: June 2007

Poverty is ‘big business’. Donor funds are set to increase substantially as the UN millennium targets—to eradicate extreme poverty and halve the number of people suffering from hunger by 2015—seem ever more out of reach. Small wonder
that social science methods to assess levels of poverty and the results of development projects have become a hot issue, too. As much of the research on poverty directly feeds into policy making and donor strategies, people are rightly concerned about its quality. Anthropology has a stake in this debate: despite the hegemony of quantitative methods in development research, participatory rural appraisals and poverty assessments have always drawn upon anthropological methods. One might wonder what happens to these qualitative methods in research that aims to establish quantitative levels of poverty.
Gauging inequality among pastoralists
Authors: Spencer Paul
Published: June 2007

Poverty is a relative concept that is most meaningful within the context of social inequality in a particular culture. Among pastoralists in east Africa, often with mixed economies and herds that tend to fluctuate erratically over time, the problem of assessing poverty and wealth can be resolved by examining profiles of polygyny to provide a comparable index of wealth. Several profiles are examined in relation to a mathematical model based on the binomial series, with an emphasis on its social rather than mathematical implications. These series are especially apt because they closely follow the distribution of wives in a substantial sample of African societies, and they reveal different types of balances between competition and conformity associated with age and with status. The purpose of this essay is to redefine the problem of poverty in terms of the social profiles of inequality, leading toward a comparative analysis between cultures.
Authenticity, hybridity, and difference
Authors: Pansters Wil G.
Published: June 2007

This article studies the transformation of the debate about national culture in twentieth-century Mexico by looking at the complex relationship between discourses of authenticity and mestizaje. The article firstly demonstrates how in the first half of the twentieth century, Mexican national identity was constructed out of a state-led program of mestizaje, thereby supposedly giving rise to a new and authentic identity, the mestizo (nation). Secondly, it is argued that the authentication project around mestizaje is riddled with paradoxes that require explanation. Thirdly, the article studies the political dimension of the authenticity discourse and demonstrates how the homogenizing and unifying forces that spring from the process of authentication played an important role in buttressing an authoritarian regime. Fourthly, the article looks at two recent developments: indigenous cultural politics and transnationalism. Here it is shown how discourses of difference, pluralism, and transnationalism are challenging the central tenets of Mexican post-revolutionary national culture and the boundaries of the national Self.
Erste Erfahrungen mit der neuen Waldgesetzgebung | Initial consequences of new forest legislation
Authors: Marti Fritz
Published: June 2007

On the 1st July 1995 the new cantonal glarner forest law came into force, the first such law based on the federal forest law of 4th October 1991. Experiences gained with regard to those articles which brought changes are of particular interest, such as the level of compensation for clearing, management of the forest, prohibition of traffic on forest roads, forestry organisation,the handling of natural catastrophes, forestry planning and the forest conservation concept.
Die überbetriebliche forstliche Planung im Kanton Glarus | All-encompassing forestry planning in the canton of Glarus
Authors: Winzeler Klemens
Published: June 2007

Forestry planning in the canton of Glarus, taking in all forest enterprises, is based on three important pillars: the cantonal forest plan (forest development plan), the cantonal forest inventory, and the mapping of forest societies. The forest plan shows individually weighted forest functions, the corresponding goals and general measures. To a certain degree the plan is the mission statement of the forest. Plant sociological site mapping is an important starting point to eliminate certain functions of the forest (yield and welfare functions).

Based on previous company inventories, a cantonal forest inventory is taking shape that will provide information on the structure, composition, as well as the condition and development of the forest. In order to optimise expenditure the density of the sample plots has been reduced by a third (i.e. one per 9 ha instead of the original 3 ha) and a changeover to a cluster with six sample plots has been put into place. Random checks are to be continued and samplings supplemented with the evaluation of the stability and surveys of young forest stands. Preliminary results are positive. Control samplings will be taken in order to ensure quality.
Integrales Naturgefahrenmanagement in einem Gebirgskanton | Integral risk management in a mountainous canton
Authors: Rageth Thomas
Published: June 2007

In recent years various natural hazards have served to shape risk management in the canton of Glarus. At the same time,within the framework of the new Forest Law, a concept had to be developed on how to deal with natural hazards. Starting point and basis for this concept is the constant taking into account of the risk situation, an important element as far as prevention is concerned. Possible damage is estimated using systematic risk assessment. With the development of an integral action concept, which includes both active and passive as well as planning measures, risk can be minimised as far as possible and combined with economic efficiency.
Lebensraum für Wildtiere – Pilotprojekte im Kanton Glarus | Living space for game – a pilot project in the canton of Glarus
Authors: Rüegg Dani , Walcher Jürg
Published: June 2007

Game has always had a special meaning for the people of the canton of Glarus. The Freiberg Kärpf is one of the oldest existing areas where hunting is prohibited, and it is also one of the biggest in Switzerland. However, designating prohibited areas cannot prevent conflict from arising between game and other yield forms. One sure sign of the conflict is the high level of browsing damage in young forest stands. The degree of damage is an indication of the disturbed balance of the living space situation, which involves all parties. The enormous storm damage caused by hurricane Vivian makes natural forest processes,such as the problem of browsing, clearly visible. New strategies have arisen in relation to game, forest and living space. Pertinent information has been gathered about living space in the project «10 Wildgebiete» and, at different stages, solutions to problems will be tried out and, if successful, implemented on a large scale.
Die bundesgerichtliche Rechtsprechung zur neuen Waldgesetzgebung | Swiss Federal Supreme Court's decisions under the new Forest Law
Authors: Nay Giusep
Published: June 2007

Compared to the old forestry laws, watched over by the local authorities (the Cantonal Forest Police Laws), since 1993 the Federal Supreme Court has passed judgement on far fewer cases. Nevertheless, since the new Forest Law came into force the court has passed a small number of judgements – in particular concerning the meaning of minimum forest area – and on gardens, parks and grassy plots. Overall, the new Forest Law can be said to be a worthy and concise codification of the old forestry law and regulations, while including earlier judgements passed by the Supreme Federal Court. However, certain provisos are justified concerning the new concept for grassy plots and parts of the law dealing with minimum criteria. The legal situation concerning minimum criteria, especially, can be seen as unsatisfactory. This is because of the wide discretionary room granted to cantons of undifferentiated exploitation under the new Forest Laws, which, in many cases, has given rise to a legal framework, the application of which will have to be rejected by the Federal Supreme Court.
Partitioning information in a multidimensional contingency table and centring of log‐linear parameters
Authors: Zighera Jacques A.
Published: June 2007

A centring of the parameters of a log‐linear model, based on the weighted harmonic mean of the exponential transforms of the parameters, gives results more consistent with the model than the traditional centring technique arbitrarily based—by analogy with the analysis of variance—on the average of the untransformed parameters. It permits the partitioning of the total information of the table in components of the information, each corresponding with a margin appearing in the constraints. An illustration is given at the end of the article concerning the labour force in the European Community.
Applied linguistics: Optimization of semantic relations by data aggregation techniques
Authors: Warnesson Isabelle
Published: June 2007

After a short methodological presentation of similarity aggregation in automatic classification, we will present an application to computational linguistics. We will try to explain, from an existing dictionary of synonyms, how we have

defined what was, in our opinion, the meaning of the synonymous relation we wanted to reveal in a new optimized dictionary,

transformed the existing dictionary into a sequence of matrices of synonymy,

checked with an adapted algorithm (similarity aggregation technique) if the links appearing in the existing dictionary corresponded to our synonymy definition,

tried to improve the synonymous relation,

in order to propose more accurate data facilitating the management of a new dictionary and providing a classification of synonyms according to a semic separate valuation.
Exponential family non‐linear models for categorical data with errors of observation
Authors: Palmgren Juni , Ekholm Anders
Published: June 2007

We present a general framework for treating categorical data with errors of observation. We show how both latent class models and models for doubly sampled data can be treated as exponential family nonlinear models. These are extended generalized linear models with the link function substituted by an observationwise defined non‐linear function of the model parameters. The models are formulated in terms of structural probabilities and conditional error probabilities, thus allowing natural constraints when modelling errors of observation. We use an iteratively reweighted least squares procedure for obtaining maximum likelihood estimates. This is faster than the traditionally used EM algorithm and the computations can be made in GLIM.1As examples we analyse three sets of categorical data with errors of observation which have been analysed before by Ashford and Sowden,2Goodman3and Chen,4respectively.
A brownian motion model of return migration
Authors: Tapiero Charles S. , Toren Nina
Published: June 2007

This paper considers a continuous time, continuous state stochastic process to determine a theoretical model and empirical parameters for the probability distribution of remigration. A Brownian motion model is used for simplicity, with empirical findings drawn from a study of Israeli return migrants. A negative relationship between remigration (sojourn) time and the probability of return time is used to provide forecasts of remigration which can help governments who seek actively the return of their migrants to reach better decisions regarding the timing of their efforts.
Capital structure of real estate assets: Theory and empirical evidence
Authors: Raimbourg P. H.
Published: June 2007

This paper presents a model which intends to explain the capital structure of real estate assets. The model is cast in classical portfolio choice framework, but special attention is paid to the liquidity constraint. The test of this model on two assets with different capital structures (new housing and old housing in France) revealed the importance of return indicators as well as liquidity constraint in the household's financing decisions.
The use of analysis of variance procedures in biological studies
Authors: Williams Byron K.
Published: June 2007

The analysis of variance (ANOVA) is widely used in biological studies, yet there remains considerable confusion among researchers about the interpretation of hypotheses being tested. Ambiguities arise when statistical designs are unbalanced, and in particular when not all combinations of design factors are represented in the data. This paper clarifies the relationship among hypothesis testing, statistical modelling and computing procedures in ANOVA for unbalanced data. A simple two‐factor fixed effects design is used to illustrate three common parametrizations for ANOVA models, and some associations among these parametrizations are developed. Biologically meaningful hypotheses for main effects and interactions are given in terms of each parametrization, and procedures for testing the hypotheses are described. The standard statistical computing procedures in ANOVA are given along with their corresponding hypotheses. Throughout the development unbalanced designs are assumed and attention is given to problems that arise with missing cells.
An alternative description of the stochastic process generating security returns
Authors: Espahbodi Hassanali , Espahbodi Pouran , Tehranian Hassan
Published: June 2007

This research questions the appropriateness of the market model in describing the stochastic process generating security returns. A new descriptive model which considers the adaptive behaviour of economic agents and their partial adjustment to new information is proposed. Empirical results indicate that the proposed model is superior to the conventional market model in describing the returns generating process. These findings raise questions about previous studies concerning the information content of specific events or concerning the market efficiency.
Effect of superficial velocity on pressure fluctuations in a gas–solid fluidized bed: A stochastic analysis
Authors: Neogi D. , Fan L. T. , Yutani N. , Nassar R. , Walawender W. P.
Published: June 2007

The characteristics of a gas–solid fluidized bed are influenced by complicated and stochastic phenomena, e.g. jetting and the bubbling of the fluidizing medium and the motion of the fluidized particles. In this study pressure fluctuations due to the bubble movement were measured by means of a pressure probe over a range of time. The resultant time series have been analysed by determining their autocorrelation function and power spectrum with emphasis on the examination of the effect of the superficial velocity of the fluidizing gas. A stochastic model of bubble motion in a fluidized bed has been developed. This model visualizes the bubble motion in a fluidized bed to consist of the random movement, generating irregular signals, and the linear movement, generating wave‐like signals. A theoretical autocorrelation function and a power spectral density function have been derived based on the model.
Block cutpoint decomposition for markovian queueing systems
Authors: Fox Dale R.
Published: June 2007

Steady‐state probabilities of Markov Processes are computed by enumerating subgraphs of the transition diagram of the process. The presence of cutpoints in the transition diagram allows for decomposition of the problem into smaller components. Examples from queueing theory are presented. Matrix representations for these structures are also discussed.
Testing quantile‐preserving spreads
Authors: Mendelson Haim
Published: June 2007

This paper derives a two‐sample non‐parametric procedure for testing quantile‐preserving spreads. The asymptotic properties of the test statistic are studied, and the use of the test is demonstrated in comparing the dispersion of the returns on a stock‐index between months.
Presentation of problem: Performance of jitter in discriminating between normal and dysphonic speakers
Authors: Schoentgen Jean
Published: June 2007

The data we deal with are acoustic feature values computed from speech signals produced by normal control speakers and speakers suffering from a laryngeal pathology. The problem is (i) to compare the discriminatory performance of a given acoustic feature with other features of the same family; (ii) to compare the performance of corresponding features in studies carried out on corpora which were not identical and which did not contain the same number of speakers; (iii) to express quantitatively the share of laryngeal pathologies which could be detected reliably by acoustic means alone. We propose to accomplish tasks (i) to (iii) by separating pooled control and risk groups on the basis of the acoustic feature values alone and by evaluating the quality of approximation of the original groups so realized. In order to evaluate this quality we compute a merit factor satisfying the following properties: (1) to be independent of the number of speakers contained in the pooled control and risk groups; (2) to increase and decrease linearly with the detection and false alarm rates, respectively; (3) to take on values between 0 (no discrimination at all) and 1 (perfect discrimination). We also address the question of the confidence one may have in the merit factor values so achieved, i.e. we describe a method of computing the probability that a merit factor value might have been realized by chance alone.
Clusterwise aggregation of relations
Authors: Gaul Wolfgang , Schader Martin
Published: June 2007

In this paper we handle the general problem of finding q(> 1) central relations on a set of objects which best fit the information contained in a finite number of given relations on that set. The proposed CAR (clusterwise aggregation of relations) algorithm allows one to consider the well‐known situation of determining a single central relation as a special case (q = 1) and takes into account the fact that the representation of appropriately selected subsets of relations by different central relations can provide additional insights into whether different clusters or segments of relations exist in the given set of relations. Two examples demonstrate the usefulness of the suggested approach.
Prognostic of glial tumours
Authors: Commenges D. , Dartigues J. F. , Rossi Carla
Published: June 2007

We deal with the problem of finding a suitable model to predict survival of patients suffering from glial tumours as a function of several covariates.

Estimation is based upon a retrospective study on 192 patients. Data were collected in the Hospital of Bordeaux and are analysed by Commenges and Dartigues1using a Cox model.

In the present paper we use dynamic Bayesian models which allow effects of the covariates to change with time through a stochastic structure.

The survival function at one year is also calculated as a function of the covariates with the highest prognostic values and two factors (linear combinations of the covariates) are identified which synthesize information related to the general state of the patient (age, first symptom, etc.) and the characteristics of the tumour (diameter, localization, etc.), respectively. Survival at one year is then calculated as function of the two factors. Results are reported in tabular and graphic forms.
Statistical methods in multi‐speaker automatic speech recognition
Authors: Boyer A. , Di Martino J. , Divoux P. , Haton J. P. , Mari J. F. , Smaili K.
Published: June 2007

Automatic speech recognition and understanding (ASR) plays an important role in the framework of man‐machine communication. Substantial industrial developments are at present in progress in this area. However, after 40 years or so of efforts several fundamental questions remain open. This paper is concerned with a comparative study of four different methods for multi‐speaker word recognition: (i) clustering of acoustic templates, (ii) comparison with a finite state automaton, (iii) dynamic programming and vector quantization, (iv) stochastic Markov sources. In order to make things comparable, the four methods were tested with the same material made up of the ten digits (0 to 9) pronounced four times by 60 different speakers (30 males and 30 females). We will distinguish in our experiments between multi‐speaker systems (capable of recognizing words pronounced by speakers that have been used during the training phase of the system) and speaker‐independent systems (capable of recognizing words pronounced by speakers totally unknown to the system). Half of the corpus (15 male and 15 female) were used for training, and the remaining part for test.
Model of traffic flow and blocking probability analysis of an m‐asymmetrical two stage incomplete link system
Authors: Tralhǎo Lino M. , Craveirinha José F. , Clímaco Joáo N.
Published: June 2007

In the first part of this study we present and review a simplified model for the traffic flow between the switches of a modular switching system. In the second part, an approximated model for calculating the blocking probability on a system with this type of architecture is presented and then generalized to a structure here defined as an m‐asymmetrical incomplete link system. The model is based on the probabilistic hypothesis of Jacobaeus and leads to a system of formulae which may be calculated using a computing language allowing for recursive subprograms.
Factors affecting the demand for softwood lumber in the united states
Authors: Uri Noel D. , Boyd Roy
Published: June 2007

This study sets out to examine whether the demand for softwood lumber in the United States is responsive to various market factors including the price of softwood lumber, the price of other building materials, and the level of economic activity (e.g. housing starts). Concern in the analysis is focused on overcoming some of the methodological shortcomings found in previous studies of this issue. The results are conclusive. The quantity of softwood lumber demanded does respond to the various economic factors considered. Moreover, when the structural stability of the estimated relationships is investigated, the results suggest that the demand for softwood lumber regionally in the United States has remained unaltered over the sample period (1950–1985).
A strategic r&d planning model with an application to an energy research organization
Authors: Chao Hung‐Po , Peck Stephen C. , Steve Wan Y.
Published: June 2007

This paper describes a two‐stage strategic planning model for determining the optimal R&D portfolio in the presence of both exploratory and developmental research projects. An example is illustrated in the context of energy research. Research portfolios are analysed using a Bayesian approach in which probability assessments are updated as new information generated by exploratory research becomes available. Useful insights are obtained through sensitivity analysis. It is found that exploratory research tends to exhibit a lumpy characteristic.
Some open problems in the design and use of modern production systems
Authors: Harhalakis G. , Proth J. M.
Published: June 2007

During the past two decades, manufacturing systems have moved towards automation, integration and modularity. These trends will certainly continue in the future due to the constraints of the market and to evolution of resources and worker requirements. As a consequence, the design and use of manufacturing systems are increasingly expensive. Numerous methods and tools have been developed to face up to this situation, but some complementary aids could be provided for designers and manufacturing engineers. The goal of this paper is to present important open problems whose solutions could certainly significantly improve the design and use of modern production systems.
A review of the numerical calculation of ruin probabilities by means of recursions
Authors: Steenackers A. , Goovaerts M.
Published: June 2007

In this review we consider the classical model for ruin probabilities describing the danger of an insurance portfolio. We give a description of the existing recursive methods for calculating ruin probabilities both with finite and infinite planning horizons.
Stochastic signal analysis: Numerical representation and applications to system theory
Authors: Valderrama Mariano J.
Published: June 2007

Alternative procedures for representing a stochastic signal as a denumerable series with uncorrelated terms are developed. The study includes considerations about parametric rescaling and its repercussions on the orthogonal expansion, as well as numerical techniques for approaching such an expansion. In addition, applications to the Gaussian characterization of stochastic signals, filtering and stochastic modelling are treated.
Improving two theorems of bose on difference families
Authors: Buratti Marco
Published: June 2007

In [2] R. C. Bose gives a sufficient condition for the existence of a (q, 5, 1) difference family in (GF(q), +)—where q ≡ 1 mod 20 is a prime power — with the property that every base block is a coset of the 5th roots of unity. Similarly he gives a sufficient condition for the existence of a (q, 4, 1) difference family in (GF(q, +)—where q ≡ 1 mod 12 is a prime power — with the property that every base block is the union of a coset of the 3rd roots of unity with zero. In this article we replace the mentioned sufficient conditions with necessary and sufficient ones. As a consequence, we obtain new infinite classes of simple difference families and hence new Steiner 2‐designs with block sizes 4 and 5. In particular, we get a (p4α, 5, 1)‐DF for any odd prime p ≡ 2, 3 (mod 5), and a (p2α, 4, 1)‐DF for any odd prime p ≡ 2 (mod 3). © 1995 John Wiley & Sons, Inc.
A generalization of the ray‐chaudhuri‐wilson theorem
Authors: Snevily Hunter S.
Published: June 2007

Let K = {k1,…,kr} and L = {l1,…,ls} be two sets of non‐negative integers and assume ki > lj for every i,j. Let F be an L‐intersecting family of subsets of a set of n elements. Assume the size of every set in F is a number from K. We conjecture that |F| ⩽ (ns). We prove that our conjecturer is true for any K. (with min ki ⩾ s) when L = {0,1,…,s − 1}. We also show that for any K and any L, (with min ki > max lj)

CALLING STATEMENT :

© 1995 John Wiley & Sons, Inc.
An inequality involving the vertex arboricity and edge arboricity of a graph
Authors: Burr Stefan A.
Published: June 2007

Let a(G) and a1(G) denote the vertex arboricity and the edge arboricity of G, respectively. The inequality a(G) ⩽ a1(G) is proved, and this is sharp. Two related inequalities, involving another parameter, are also proved.
A new sufficient condition for hamiltonian graphs
Authors: Fraisse Pierre
Published: June 2007

We prove that a k‐connected graph of order n, such that the number of neighbors of every independent set of k vertices is greater than (k(n – 1))/(k + 1) is hamiltonian.
Minimal ordered triangulations of surfaces
Authors: Magajna Zlatan , Mohar Bojan , Pisanski Tomaž
Published: June 2007

A finite simplicial complex is orderable if its simplices are the chains of a poset. For each closed surface an orderable triangulation is given that is minimal with respect to the number of vertices. The construction of minimal ordered triangulations implies that for each surface S the minimal number of vertices of a bipartite graph, which has a quadrilateral embedding into S, is equal to b(S) = ⌈4 + (16 – 8χ)1/2⌉, where χ is the Euler characteristic of S.
Extremal problems concerning transformations of the edges of the complete hypergraphs
Authors: Caro Yair
Published: June 2007

We consider extremal problems concerning transformations of the edges of complete hypergraphs. We estimate the order of the largest subhypergraph K such that for every edge e ϵ E(K), f(e) ∉ E(K), assuming f(e) ≠ e. Several extensions and variations of this problem are also discussed here.
Note on the reconstruction of vertex colored graphs
Authors: Taylor R.
Published: June 2007

We show that if the Reconstruction Conjecture is true for uncolored (vertex‐monochromatic) simple graphs, then it is also true for vertex‐colored simple graphs.
Edge‐colored saturated graphs
Authors: Hanson D. , Toft B.
Published: June 2007

A graph G is (k1, k2, …, kt)‐saturated if there exists a coloring C of the edges of G in t colors 1, 2, …, t in such a way that there is no monochromatic complete ki‐subgraph K of color i, 1 ⩽ i ⩽ t, but the addition of any new edge of color i, joining two nonadjacent vertices in G, with C, creates a monochromatic K of color i, 1 ⩽ i ⩽ t. We determine the maximum and minimum number of edges in such graphs and characterize the unique extremal graphs.
Hierarchy for imbedding‐distribution invariants of a graph
Authors: Gross Jonathan L. , Furst Merrick L.
Published: June 2007

Most existing papers about graph imbeddings are concerned with the determination of minimum genus, and various others have been devoted to maximum genus or to highly symmetric imbeddings of special graphs. An entirely different viewpoint is now presented in which one seeks distributional information about the huge family of all cellular imbeddings of a graph into all closed surfaces, instead of focusing on just one imbedding or on the existence of imbeddings into just one surface. The distribution of imbeddings admits a hierarchically ordered class of computable invariants, each of which partitions the set of all graphs into much finer subcategories than the subcategories corresponding to minimum genus or to any other single imbedding surface. Quite low in this hierarchy are invariants such as the average genus, taken over all cellular imbeddings, and the average region size, where “region size” means the number of edge traversals required to complete a tour of a region boundary. Further up in the hierarchy is the multiset of duals of a graph. At an intermediate level are the “imbedding polynomials.” The hierarchy is explored, and several specific calculations of the values of some of the invariants are provided. The main results are concerned with the amount of work needed to derive one invariant from another, when possible, and with principles for computing the algebraic effect of adding an edge or of otherwise combining two graphs.
Class‐reconstruction of total graphs
Authors: Bange David W. , Barkauskas Anthony E. , Host Linda H.
Published: June 2007

It is shown that given any vertex‐deleted total graph, every reconstruction into a total graph by the addition of a vertex yields the original total graph. The proof indicates how the reconstruction can be done.
On the Interval Number of a Triangulated Graph
Authors: Andreae Thomas
Published: June 2007

The interval number of a simple undirected graph G, denoted i(G), is the least nonnegative integer r for which we can assign to each vertex in G a collection of at most r intervals on the real line such that two distinct vertices v and w of G are adjacent if and only if some interval for v intersects some interval for w. For triangulated graphs G, we consider the problem of finding a sharp upper bound for the interval number of G in terms of its clique number ω(G). The following partial results are proved. (1) For each triangulated graph G, i(G) ⩽ ⌈ω(G)/2⌉ + 1, and this is best possible for 2 ⩽ ω(G) ⩽ 6. (2) For each integer m ⩾ 2, there exists a triangulated graph G with ω(G) = m and i(G) > m1/2.
Bidegreed graphs are edge reconstructible
Authors: Myrvold W. J. , Ellingham M. N. , Hoffman D. G.
Published: June 2007

An edge‐deleted subgraph of a graph G is a subgraph obtained from G by the deletion of an edge. The Edge Reconstruction Conjecture asserts that every simple finite graph with four or more edges is determined uniquely, up to isomorphism, by its collection of edge‐deleted subgraphs. A class of graphs is said to be edge reconstructible if there is no graph in the class with four or more edges that is not edge reconstructible. This paper proves that bidegreed graphs (graphs whose vertices all have one of two possible degrees) are edge reconstructible. The results are then generalized to show that all graphs that do not have three consecutive integers in their degree sequence are also edge reconstructible.
A new 5‐arc‐transitive cubic graph
Authors: Conder Marston
Published: June 2007

A connected cubic graph having 75,600 vertices is shown to exist, with the symmetric group S10 as a group of automorphisms acting transitively on its 5‐arcs. This graph is not bipartite, nor is it a covering of any other known 4‐ or 5‐arc‐transitive graph.
Hypergraph planarity and the complexity of drawing venn diagrams
Authors: Johnson D. S. , Pollak H. O.
Published: June 2007

We introduce two new notions of planarity for hypergraphs based on dual generalizations of the standard Venn diagram. These definitions are illustrated by results concerning the existence and nonexistence of such diagrams for certain classes of hypergraphs. We conclude by showing that the general problem of determining whether such diagrams exist is NP‐complete.
On the hamiltonian path graph of a graph
Authors: Hendry George R. T.
Published: June 2007

The hamiltonian path graph H(F) of a graph F is that graph having the same vertex set as F and in which two vertices u and v are adjacent if and only if F contains a hamiltonian u − v path. First, in response to a conjecture of Chartrand, Kapoor and Nordhaus, a characterization of nonhamiltonian graphs isomorphic to their hamiltonian path graphs is presented. Next, the maximum size of a hamiltonian graph F of given order such that K̄d ⊆ H(F) is determined. Finally, it is shown that if the degree sum of the endvertices of a hamiltonian path in a graph F with at least five vertices is at least |V(F)| + t(t ⩾ 0), then H(F) contains a complete subgraph of order t + 4.
The maximum interval number of graphs with given genus
Authors: Scheinerman Edward R.
Published: June 2007

The interval number of a graph G, denoted i(G), is the least positive integer t such that G is the intersection graph of sets, each of which is the union of t compact real intervals. It is known that every planar graph has interval number at most 3 and that this result is best possible. We investigate the maximum value of the interval number for graphs with higher genus and show that the maximum value of the interval number of graphs with genus g is between ⌈√g⌉ and 3 + ⌈√3g⌉. We also show that the maximum arboricity of graphs with genus g is either 1 + ⌈√3g⌉ or 2 + ⌈√3g⌉.
An improved edge bound on the interval number of a graph
Authors: Spinrad Jeremy R. , Vijayan G. , West Douglas B.
Published: June 2007

The upper bound on the interval number of a graph in terms of its number of edges is improved. Also, the interval number of graphs in hereditary classes is bounded in terms of the vertex degrees.
On unavoidable digraphs in orientations of graphs
Authors: Bloom Gary S. , Burr Stefan A.
Published: June 2007

Let G be a graph, and let D be a directed graph. Write G → D to mean that, no matter how the edges of G are given orientations, a copy of D must appear as a subgraph of the resulting oriented graph. It is proved that among all G for which G → D, the minimum chromatic number is equal to the minimum k for which Kk → hom(D), where hom(D) is the set of homomorphs of D. Next, necessary and sufficient conditions are given for a directed graph to have a homomorphism into a given transitive tournament, directed path, or directed cycle. These results are then applied to various cases of the above theorem. In particular, the minimum chromatic number is evaluated whenever D is an oriented forest, and all D are characterized for which the minimum chromatic number is no more than three.
Enumeration and generation of a class of regular digraphs
Authors: Ramanath M. V. S. , Walsh T. R.
Published: June 2007

We study the class of directed graphs that have indegree = outdegree = 2 at every vertex. These digraphs can be decomposed uniquely into “alternating cycles”, we use this decomposition to present efficient techniques for counting and generating them. The number (up to isomorphism) of these digraphs and the number of connected ones on up to 20 vertices have been computed and are presented.
An upper bound for the harmonious chromatic number of a graph
Authors: Lee Sin‐Min , Mitchem John
Published: June 2007

An upper bound for the harmonious chromatic number of a graph G is given. Three corollaries of the theorem are theorems or improvements of the theorems of Miller and Pritikin.
Ki‐covers. II. Ki‐perfect graphs
Authors: Conforti Michele , Corneil Derek Gordon , Mahjoub Ali Ridha
Published: June 2007

AKi is a complete subgraph of size i. A Ki‐cover of a graph G(V, E) is a set C of Ki−1s of G such that every Ki in G contains at least one Ki−1 in C. ci(G) is the cardinality of a smallest Ki‐cover of G. A Ki‐packing of G is a set of Kis such that no two Kis have i − 1 nodes in common. pi(G) is the cardinality of a largest Ki‐packing of G. Let Fi(G) denote the set of Kis in G and define ci(F) and pi(F) analogously for F ⊆ Fi(G). G is Ki‐perfect if ∀F ⊆ Fi(G), ci(F) = pi(F). The K2‐perfect graphs are precisely the bipartite graphs. We present a characterization of Ki‐perfect graphs that is similar to the Strong Perfect Graph Conjecture, and explore the relationships between Ki‐perfect graphs and normal hypergraphs. Furthermore, if iA denotes the 0 − 1 matrix of G where the rows are the elements of Fi−1(G) that belong to at least one Ki and the columns are the elements of Fi(G), then we show that iA is perfect iff G is a Ki‐perfect graph. We also characterize the Ki‐perfect graphs for which iAis balanced.
Search algorithm for Ramsey graphs by union of group orbits
Authors: Radziszowski Stanisław P. , Kreher Donald L.
Published: June 2007

An algorithm for the construction of Ramsey graphs with a given automorphism group G is presented. To find a graph on n vertices with no clique of k vertices, Kk, and no independent set of l vertices, ¯Kl, k, l ≤ n, with an automorphism group G, a Boolean formula α based on the G‐orbits of k‐subsets and l‐subsets of vertices is constructed from incidence matrices belonging to G. This Boolean formula is satisfiable if and only if the desired graph exists, and each satisfying assignment to α specifies a set of orbits of pairs of vertices whose union gives the edges of such a graph. Finding these assignments is basically equivalent to the conversion of α from CNF to DNF (conjunctive to disjunctive normal form). Though the latter problem is NP‐hard, we present an “efficient” method to do the conversion for the formulas that appear in this particular problem. When G is taken to be the dihedral group Dn for n ≤ 101, this method matches all of the previously known cyclic Ramsey graphs, as reported by F. R. K. Chung and C. M. Grinstead [“A Survey of Bounds for Classical Ramsey Numbers,” Journal of Graph Theory, 7 (1983), 25–38], in dramatically smaller computer time when compared to the time required by an exhaustive search. Five new lower bounds for the classical Ramsey numbers are established: R(4, 7) ⩾ 47, R(4, 8) ⩾ 52, R(4, 9) ⩾ 69, R(5,7) ⩾ 76, and R(5, 8) ⩾ 94. Also, some previously known cyclic graphs are shown to be unique up to isomorphism.
On resolvable tree‐decompositions of complete graphs
Authors: Lonc Zbigniew
Published: June 2007

A partition of the edge set of a graph H into subsets inducing graphs H1,…,Hs isomorphic to a graph G is said to be a G‐decomposition of H. A G‐decomposition of H is resolvable if the set {H1,…,Hs} can be partitioned into subsets, called resolution classes, such that each vertex of H occurs precisely once in each resolution class. We prove that for every graceful tree T of odd order the obvious necessary conditions for the existence of a resolvable T‐decomposition of a complete graph are asymptotically sufficient. This generalizes the results of Horton and Huang concerning paths and stars.
On the interval number of a chordal graph
Authors: Scheinerman Edward R.
Published: June 2007

The interval number of a (simple, undirected) graph G is the least positive integer t such that G is the intersection graph of sets, each of which is the union of t real intervals. A chordal (or triangulated) graph is one with no induced cycles on 4 or more vertices. If G is chordal and has maximum clique size ω(G) = m, then i(G) ⩽ [1 + o(1)]m/log2 m and this result is best possible, even for split graphs (chordal graphs whose complement is also chordal).
Some results on odd factors of graphs
Authors: Yuting Cui , Kano Mikio
Published: June 2007

A {1, 3, …,2n − 1}‐factor of a graph G is defined to be a spanning subgraph of G, each degree of whose vertices is one of {1, 3, …, 2n − 1}, where n is a positive integer. In this paper, we give a sufficient condition for a graph to have a {1, 3, …, 2n − 1}‐factor.
A dirac‐type theorem for squares of graphs
Authors: Traczyk Tomasz
Published: June 2007

We prove that if G is a connected graph with p vertices and minimum degree greater than max (p/4 − 1,3) then G2 is pancyclic. The result is best possible of its kind.
Existence of Δλ‐cycles and Δλ‐paths
Authors: Broersma H. J.
Published: June 2007

A Cycle C of a graph G is called a Dλ‐cycle if every component of G − V(C) has order less than λ A Dλ‐path is defined analogously. Dλ‐cycles and Dλ‐paths were introduced by Veldman. Here a cycle C of a graph G is called a Δλ‐cycle if all vertices of G are at distance less than λ from a vertex of C. A Δλ‐path is defined analogously. In particular, in a connected graph, a Δλ‐cycle is a Δλ‐Cycle and a Δλ‐Path is a Δ‐path. Furthermore, a Δ1‐cycle is a Hamilton cycle and a Δ1path is a Hamilton path. Necessary conditions and sufficient conditions are derived for graphs to have a Δλ‐cycle or Δλ‐path. The results are analogues of theorems on Dλ‐cycles and Dλ‐paths. In particular, a result of Chvátal and Erdös on Hamilton cycles and Hamiiton paths is generalized. A recent conjecture of Bondy and Fan is settled.
An upper bound for some ramsey numbers
Authors: Thomason Andrew
Published: June 2007

New upper bounds for the ramsey numbers r(k, l) are obtained. In particular it is shown there is a constant A such that
magnified image
An extremal problem on Kr‐free graphs
Authors: Frankl Peter , Pach János
Published: June 2007

Let r, t ⩾ 2 be integers and c a constant, 0 < c ⩽ (r ‐ 2)/(r − 1). Suppose that G is a Kr‐free graph on n vertices in which any t distinct vertices have at most cn common neighbors. Here an asymptotically best bound is obtained for the maximal number of edges in such graphs. This solves a problem of Babai et al. in a more general form.
A note on graphs with diameter‐preserving spanning trees
Authors: Buckley Fred , Lewinter Martin
Published: June 2007

The distance between a pair of vertices u, v in a graph G is the length of a shortest path joining u and v. The diameter diam(G) of G is the maximum distance between all pairs of vertices in G. A spanning tree T of G is diameter preserving if diam(T) = diam(G). In this note, we characterize graphs that have diameter‐preserving spanning trees.
Star chromatic number
Authors: Vince A.
Published: June 2007

A generalization of the chromatic number of a graph is introduced such that the colors are integers modulo n, and the colors on adjacent vertices are required to be as far apart as possible.
Edge‐connectivity in p‐partite graphs
Authors: Volkmann Lutz
Published: June 2007

Let G = (V, E) be a finite, simple p‐partite graph with minimum degree δ and edge‐connectivity γ. It is proved that if |V| ⩽ (2pδ)/(p ‐ 1) ‐ 2 or in special cases that if |V| ⩽ (2pδ)/(p ‐ 1) ‐ 1, then λ = δ. It is further shown that this result is best possible.
Paths in bipartite graphs with color‐inverting involutions
Authors: Sabidussi Gert
Published: June 2007

We consider connected bipartite graphs that have a color‐inverting involution and do not contain an induced path of length 5. It is shown that such graphs have a color‐preserving involution or a dominating edge, or else contain one of two simple forbidden subgraphs.
Graphs with intrinsic s3 convexities
Authors: Bandelt Hans‐Jürgen
Published: June 2007

Separation properties for some intrinsic convexities of graphs are investigated. The most natural convexities defined on a graph are the induced path convexity and the geodesic convexity. A set A of vertices is convex with respect to the former convexity if A contains every induced path connecting two vertices of A. In particular, a characterization of those graphs is given in which all such convex sets are the intersections of halfspaces (i.e., convex sets with convex complements).
A strengthening of Kikustapos;s theorem
Authors: Hendry George R. T.
Published: June 2007

We consider connected, locally connected graphs in which the maximum and minimum degrees differ by at most one and do not exceed five. It is shown that if C is a nonhamiltonian cycle in such a graph G, then there exists a cycle Capos; in G such that V(C) ⊆ V(Capos;) and /V(Capos;) = /(C) + 1.
Regular graphs with prescribed chromatic number
Authors: Caccetta L. , Pullman N. J.
Published: June 2007

We determine the minimum number of edges in a regular connected graph on n vertices, containing a complete subgraph of order k ≤ n/2. This enables us to confirm and strengthen a conjecture of P. Erdös on the existence of regular graphs with prescribed chromatic number.