bluuebunny/crossref_metadata_2025_split huggingface dataset:
Existence of certain skew room frames with application to weakly 3‐chromatic linear spaces
Authors: Rodger C. A. , Wantland E. B. , Chen K. , Zhu L. 
Published: June 2007

AbstractIt is shown that for any even integer n ≥ 16 and for some b ≥ 1, there exists a skew Room frame of type 2a 4b with n = 2a + 4b. As an application, we show that for any integer v ≡ 1,4 (mod 12), there exists a weakly 3‐chromatic linear space with all lines having size 4 iff v > 16. This answers an open problem posed by Colbourn and Rosa. © 1994 John Wiley & Sons, Inc.
The structure of symmetry groups of GK(2n, G)
Authors: Duncan D. , Ihrig E. 
Published: June 2007

AbstractThe automorphism groups of the one‐factorizations GK(2n,G) are computed. It is shown that every 1‐factorization of K2n with a subgroup of the automorphism group that acts sharply 2‐transitively on the one‐factors must be GK(pm + 1, (Zp)m) for some odd prime p. © 1994 John Wiley & Sons, Inc.
Large sets of coverings
Authors: Etzion Tuvi 
Published: June 2007

AbstractLarge sets of packings were investigated extensively. Much less is known about the dual problem, i.e., large sets of coverings. We examine two types of important questions in this context; what is the maximum number of disjoint optimal coverings? and what is the minimum number of optimal coverings for which the union covers the space? We give various constructions which give the optimal solutions and some good upper and lower bounds on both questions, respectively. © 1994 John Wiley & Sons, Inc.
Theory of perpendicular arrays
Authors: Bierbrauer Jürgen , Edel Yves 
Published: June 2007

AbstractThe cryptographical theory of unconditional secrecy and authentication is based on design‐like structures called perpendicular arrays in the combinatorial literature. In order to meet the cryptographical requirements some additional and rather natural homogeneity conditions have to be satisfied. We develop a theory of these structures. Topics include bounds on the size, recursive and direct constructions using designs and permutation groups, as well as a link to Room cubes. © 1994 John Wiley & Sons, Inc.
Balanced arrays of strength two and nested (r, λ)‐designs
Authors: Kuriki Shinji , Fuji‐Hara Ryoh 
Published: June 2007

AbstractAn (r,λ)‐design with mutually balanced nested subdesigns (for brevity, (r,λ)‐design with MBN) is introduced firstly in this article. It is shown that an r,λ‐design with MBN is equivalent to a balanced array of strength 2 with s symbols. By the use of a nested design and an orthogonal array, a construction of an r,λ‐design with MBN is given. A direct construction of such an (r,λ)‐design, based on the result obtained by Wilson [15], is also given. By these constructions, new balanced arrays with s ≥ 3 are presented. © 1994 John Wiley & Sons, Inc.
A small basis for four‐line configurations in steiner triple systems. Dedicated to the memory of gemma holly griggs
Authors: Grannell M. J. , Griggs T. S. , Mendelsohn E. 
Published: June 2007

AbstractFormulae for the numbers of two, three, and four‐line configurations in a Steiner triple system of order v, STS(v), are given. While the formulae for two and three‐line configurations depend only on v, the same is true for only 5 of the 16 four‐line configurations. For the other 11 and fixed v, the number of occurrences of any one of them, in particular the Pasch configuration, determines the number of occurrences of all the others. © 1995 John Wiley & Sons, Inc.
Existence results for near resolvable designs
Authors: Furino Steven 
Published: June 2007

AbstractA near resolvable design, NRB(v, k), is a balanced incomplete block design whose block set can be partitioned into v classes such that each class contains every point of the design but one, and each point is missing from exactly one class. The necessary conditions for the existence of near resolvable designs are v ≡ 1 mod k and λ = k − 1. These necessary conditions have been shown to be sufficient for k ϵ {2,3,4} and almost always sufficient for k ϵ {5,6}. We are able to show that there exists an integer n0(k) so that NRB(v,k) exist for all v > n0(k) and v ≡ 1 mod k. Using some new direct constructions we show that there are many k for which it is easy to compute an explicit bound on n0(k). These direct constructions also allow us to build previously unknown NRB(v,5) and NRB(v,6). © 1995 John Wiley & Sons, Inc.
Existence of frame sols of type 2nu1
Authors: Yunqing Xu , Lie Zhu 
Published: June 2007

AbstractAn SOLS (self‐orthogonal latin square) of order n with n1 missing sub‐SOLS (holes) of order hi (1 ⩽ i ⩽ k), which are disjoint and spanning (i.e., Σ 1⩽i⩽knihi = n), is called a frame SOLS and denoted by FSOLS(h1n1 h2n2 …hknk). In this article, it is shown that for u ⩾ 2, an FSOLS(2nu1) exists if and only if n ⩾ 1 + u. © 1995 John Wiley & Sons, Inc.
On the classification of linear spaces of order 11
Authors: Pietsch Ch. 
Published: June 2007

AbstractA linear space of order n is a pair (V,B), where V is a finite set of n elements and B is a set of subsets of V such that each 2‐subset of V is contained in exactly one element of B. The exact number of nonisomorphic linear spaces was known up to order 10. Betten and Braun [1] found that there exist at least 232,923 nonisomorphic linear spaces of order 11. We used a generalization of Ivanov's algorithm for the enumeration of block designs in order to construct all 232,929 linear spaces of order 11. The method used will be described and some data concerning line types, line lengths, and orders of automorphism groups is listed. © 1995 John Wiley & Sons, Inc.
Multiplier theorems
Authors: Arasu K. T. , Xiang Qing 
Published: June 2007

AbstractWe state and prove a multiplier theorem for a central element A of ZG, the group ring over Z of a group G. This generalizes most previously known multiplier theorems for difference sets and divisible difference sets. We also provide applications to show that our theorem provides new multipliers and establish the nonexistence of a family of divisible difference sets which correspond to elliptic semiplanes admitting a regular collineation group. © 1995 John Wiley & Sons, Inc.
New constructions for covering designs
Authors: Gordon Daniel M. , Patashnik Oren , Kuperberg Greg 
Published: June 2007

AbstractA(v, k, t) covering design, or covering, is a family of k‐subnets, called blocks, chosen from a v‐set, such that each t‐subnet is contained in at least one of the blocks. The number of blocks is the covering's size, and the minimum size of such a covering is denoted by C(v,k,t). This paper gives three new methods for constructing good coverings; a greedy algorithm similar to Conway and Sloane's algorithm for lexicographic codes [6], and two methods that synthesize new coverings from preexisting ones. Using these new methods, together with results in the literature, we build tables of upper bounds on C(v,k,t) for v ⩽ 32, k ⩽ 16, and t ⩽ 8. © 1995 John Wiley & Sons, Inc.
A remark on the uniqueness of embeddings of linear spaces into desarguesian projective planes
Authors: Metsch Klaus 
Published: June 2007

AbstractSuppose that q ⩾ 2 is a prime power. We show that a linear space with a(q + 1)2 + (q + 1) points, where a ⩾ 0.763, can be embedded in at most one way in a desarguesian projective plane of order q. © 1995 John Wiley & Sons, Inc.
Smoothness versus skewness in block designs with an application to tournaments
Authors: Robinson David G. 
Published: June 2007

AbstractThe quadratic residue designs over GF(7) and GF(11) are shown to be the only quasismooth skew (Hadamard) designs, thus setting a conjecture of Herzog and Reid concerning the existence of so‐called “nearly triply regular” tournaments. © 1995 John Wiley & Sons., Inc.
A. translation of J. X. Lu's “an existence theory for resolvable balanced incomplete block designs”
Authors: Lee Therese C. Y. , Furino Steven C. 
Published: June 2007

AbstractIn 1984, J. X. Lu proved the following statement. Given any k and λ, there exists a constant c(k, λ) such that an RB[v,k,λ] exists for all v > c(k,λ) satisfying the usual necessary conditions. Lu's paper was written in Chinese and, unfortunately, its accessibility is limited. We have translated Lu's paper into English and have also given a new interpretation of his constructions for resolvable block designs. © 1995 John Wiley & Sons, Inc.
Calibration of PRECIS in employing future scenarios in Bangladesh
Authors: Nazrul Islam Md. , Rafiuddin M. , Ahmed Ahsan Uddin , Kolli Rupa Kumar 
Published: June 2007

AbstractProviding Regional Climates for Impacts Studies (PRECIS) is a regional climate model, which is used for the simulation of regional‐scale climatology at high resolution (i.e. 50‐km horizontal resolution). The calibration of rainfall and temperature simulated by PRECIS is performed in Bangladesh with the surface observational data from the Bangladesh Meteorological Department (BMD) for the period 1961–1990. The Climate Research Unit (CRU) data is also used for understanding the performance of the model. The results for the period 1961–1990 are used as a reference to find the variation of PRECIS‐projected rainfall and temperature in 2071, in and around Bangladesh, as an example. Analyses are performed using the following two methods: (1) grid‐to‐grid and (2) point‐to‐point analyses. It is found that grid‐to‐grid analysis provides overestimation of PRECIS in Bangladesh because of downscaling of observed data when gridded from asymmetric low‐density data network of BMD. On the other hand, model data extracted at observational sites provide better performance of PRECIS. The model overestimates rainfall in dry and pre‐monsoon periods, whereas it underestimates it in the monsoon period. Overall, PRECIS is found to be able to estimate about 92% of surface rainfall. Model performance in estimating rainfall increases substantially with the increase in the length of time series of datasets. Systematic cold bias is found in simulating the annual scale of the surface temperature. In the annual scale, the model underestimates temperature of about 0.61 °C that varies within a range of + 1.45 °C to − 3.89 °C in different months. This analysis reveals that rainfall and temperature will be increased in Bangladesh in 2071. On the basis of the analyses, look‐up tables for rainfall and temperature were prepared in a bid to calibrate PRECIS simulation results for Bangladesh. The look‐up tables proposed in this analysis can be employed in the application of the projected rainfall and temperature in different sectors of the country. These look‐up tables are useful only for the calibration of PRECIS simulation results for future climate projection for Bangladesh. Copyright © 2007 Royal Meteorological Society
A pre‐deforestation pollen‐climate calibration model for New Zealand and quantitative temperature reconstructions for the past 18 000 years BP
Authors: Wilmshurst Janet M. , McGlone Matt S. , Leathwick John R. , Newnham Rewi M. 
Published: June 2007

AbstractQuantification of modern pollen rain–vegetation–climate relationships in New Zealand has been complicated by human destruction of at least 75% of the original forest cover since ca. 750 years BP, causing contemporary pollen rain over large areas to bear little resemblance to the pre‐human vegetation. We use a pre‐deforestation pollen database to circumvent this complication. The relationships between the pre‐deforestation pollen assemblages and six climatic variables were explored using principal components analysis and constrained regressions (redundancy analyses). Quantitative estimates of the most significant climate variable (mean annual temperature) were made at seven lowland to montane fossil pollen sites from throughout New Zealand using the modern analogue technique and a transfer function. These showed an initial increase in mean annual temperature after 18 000 cal. yr BP, a cooling at the time of the Antarctic Cold Reversal (centred on 13 500 cal. yr BP) and continuation of warming from ca. 12 000 cal. yr BP across the Younger Dryas chronozone, reaching a Holocene thermal optimum that may have been between 1.5 and 3°C warmer than present and lasted from 9000 to 7000 cal. yr BP depending on the site. Cooling to present‐day temperatures was well advanced by 4000–3000 cal. yr BP. Copyright © 2007 John Wiley & Sons, Ltd.
Vegetation and climate of Auckland, New Zealand, since ca. 32 000 cal. yr ago: support for an extended LGM
Authors: Newnham Rewi M. , Lowe David J. , Giles Teresa , Alloway Brent V. 
Published: June 2007

AbstractAuckland occupies a climatically sensitive position close to a major biogeographic boundary in the southern mid‐latitudes. A new pollen record from Kohuora maar crater, Auckland, displays vegetation and climatic changes for the past ca. 32 000 years. Of particular interest are the inferred climatic patterns for the first part of the interval, encompassing the Last Glacial Maximum (LGM). The Kohuora record corresponds closely with pollen records from other Auckland sites indicating that the patterns observed are at least regional in extent. It is also broadly consistent with a variety of palaeoenvironmental evidence from across New Zealand, including the glacial record from Westland, other palynological records from North Island, other palaeoecological records from the South Island, and aeolian quartz sequences from western North Island. These records show that glacial conditions prevailed across most, if not all, of New Zealand during the interval ca. 29–19 k cal. yr BP, longer and earlier than the LGM sensu stricto. We suggest that the term extended LGM (eLGM) may be more appropriate for the New Zealand region. Within this predominantly cold interval, the Auckland pollen records indicate a climatic amelioration for the interval ca. 26–24 k cal. yr BP, also consistent with other palaeocological data from Canterbury, that fall within a period of climate amelioration recognised between the first two eLGM glacial advances in Westland. We refer to this warming interval as the eLGM Interstadial. The ca. 27 k cal. yr BP Kawakawa/Oruanui tephra is instrumental in most of these inter‐site comparisons and occurs after the first peak of eLGM cooling in a short‐lived comparatively mild phase. A subsequent return to apparently colder climate in the Auckland records may indicate a volcanic cooling effect or, more likely, widespread landscape disturbance following this major eruption event. Strong correspondence between biotic responses, glacial fluctuations and aeolian quartz deposition linked to major shifts in strength and latitudinal extent of the southern westerlies suggest that both the eLGM and eLGM Interstadial may be more widely registered, at least across the Southern Ocean. Support for this assertion comes from parallel investigations in western and southernmost South America and isotopic and palaeoecological records from Southern Ocean marine cores. Recent reconstructions of the globally averaged ice‐equivalent sea‐level history are in line with this evidence from the Southern Hemisphere, suggesting that the eLGM may have a global registration. In light of these observations, we suggest a re‐examination of the defined timing of the LGM along with renewed effort to establish climatic patterns during this period and understand their causes. Copyright © 2007 John Wiley & Sons, Ltd.
Advanced Femtosecond Lasers for Industry and Science – Modern fs‐Lasers Are Sealed and Turn‐Key Systems
Authors: Renner Thomas , Lison Frank , Posthumus Jan 
Published: June 2007

AbstractFemtosecond lasers belong to the most exciting kind of lasers. They are used in science, medicine and industry where their light serves for example as optical probe for time‐resolved studies, the analysis of biological material or the micro structuring of advanced material components.
High Power Diode Lasers for Industrial Applications
Authors: Horn Wolfgang 
Published: June 2007

AbstractNew wavelengths, high brightness and increasing reliability are breaking new ground for diode lasers. The higher brightness allows direct fiber coupling of several 100 W in 200 μm and 400 μm fibers and therefore i.e. the pumping of fiber lasers. Such high power fiber coupled laser diodes combined with fast beam deflection units (galvo scanners) have been implemented in industrial processes and used for quasi‐simultaneous welding of polymers, heat treatment in the sub millimeter range or selective soldering in solar cell production. Besides pumping of solid state lasers, high power diode lasers become more and more a competitive tool for many applications in material processing.
A Remark on Ascending Chain Conditions, the Countable Axiom of Choice and the Principle of Dependent Choices
Authors: Diener Karl‐Heinz 
Published: June 2007

AbstractIt is easy to prove in ZF− (= Zermelo‐Fraenkel set theory without the axioms of choice and foundation) that a relation R satisfies the maximal condition if and only if its transitive hull R* does; equivalently: R is well‐founded if and only if R* is. We will show in the following that, if the maximal condition is replaced by the (finite ascending) chain condition, as is often the case in Algebra, the resulting statement is not provable in ZF− anymore (if ZF− is consistent). More precisely, we will prove that this statement is equivalent in ZF− to the countable axiom of choice ACω. Moreover, applying this result we will prove that the axiom of dependent choices, restricted to partial orders as used in Algebra, already implies the general form for arbitrary relations as formulated first by Teichmüller and, independently, some time later by Bernays and Tarski.Mathematics Subject Classification: 06B05, 08A65, 08B20, 03E99.
Cyclic Elements in MV‐Algebras and Post Algebras
Authors: Torrens Antoni 
Published: June 2007

AbstractIn this paper we characterize the MV‐algebras containing as subalgebras Post algebras of finitely many orders. For this we study cyclic elements in MV‐algebras which are the generators of the fundamental chain of the Post algebras.Mathematics Subject Classification: 03G20, 03G25, 06D25, 06D30, 06F15, 06F35.
Hilbert's 17th Problem for Real Closed Rings
Authors: Mathews Larry 
Published: June 2007

AbstractWe recall the characterisation of positive definite polynomial functions over a real closed ring due to Dickmann, and give a new proof of this result, based upon ideas of Abraham Robinson. In addition we isolate the class of convexly ordered valuation rings for which this characterisation holds.Mathematics Subject Classification: 03C60, 13L05, 12D15.
Recursively Enumerable Equivalence Relations Modulo Finite Differences
Authors: Nies André 
Published: June 2007

AbstractWe investigate the upper semilattice Eq* of recursively enumerable equivalence relations modulo finite differences. Several natural subclasses are shown to be first‐order definable in Eq*. Building on this we define a copy of the structure of recursively enumerable many‐one degrees in Eq*, thereby showing that Th(Eq*) has the same computational complexity as the true first‐order arithmetic.Mathematics Subject Classification: 03D25, 03D15, 03D35.
Absolute Continuity and the Uniqueness of the Constructive Functional Calculus
Authors: Bridges Douglas , Ishihara Hajime 
Published: June 2007

AbstractThe constructive functional calculus for a sequence of commuting selfadjoint operators on a separable Hilbert space is shown to be independent of the orthonormal basis used in its construction. The proof requires a constructive criterion for the absolute continuity of two positive measures in terms of test functions.Mathematics Subject Classification: 03F60, 46S30, 47S30.
The Axiom of Choice in Second‐Order Predicate Logic
Authors: Gaßner Christine 
Published: June 2007

AbstractThe present article deals with the power of the axiom of choice (AC) within the second‐order predicate logic. We investigate the relationship between several variants of AC and some other statements, known as equivalent to AC within the set theory of Zermelo and Fraenkel with atoms, in Henkin models of the one‐sorted second‐order predicate logic with identity without operation variables. The construction of models follows the ideas of Fraenkel and Mostowski. It is e. g. shown that the well‐ordering theorem for unary predicates is independent from AC for binary predicates and from the trichotomy law for unary predicates. Moreover, we show that the AC for binary predicates follows neither from the trichotomy law for unary predicates nor from Zorn's lemma for unary predicates nor from the formalization of the axiom of choice for disjoint families of sets for binary predicates, and that the trichotomy law for unary predicates does not follow from AC for binary predicates.Mathematics Subject Classification: 03B15, 03E25, 04A25.
All Finitely Axiomatizable Normal Extensions of K4.3 are Decidable
Authors: Zakharyaschevm Michael , Alekseev Alexander 
Published: June 2007

AbstractWe use the apparatus of the canonical formulas introduced by Zakharyaschev [10] to prove that all finitely axiomatizable normal modal logics containing K4.3 are decidable, though possibly not characterized by classes of finite frames. Our method is purely frame‐theoretic. Roughly, given a normal logic L above K4.3, we enumerate effectively a class of (possibly infinite) frames with respect to which L is complete, show how to check effectively whether a frame in the class validates a given formula, and then apply a Harropstyle argument to establish the decidability of L, provided of course that it has finitely many axioms.
Temporal Algebras, Pretemporal Algebras, and Modal Algebras: A Relation between Time and Necessity
Authors: Olmedo Francisco M. García , Salas Antonio J. Rodríguez 
Published: June 2007

AbstractIn this paper the structure of pretemporal algebra is used to study some aspects of temporal algebras and modal algebras. The paper contains a computational approach to finite temporal algebras and a general splitting theorem for finite temporal algebras.
Non Standard Regular Finite Set Theory
Authors: Baratella Stefano , Ferro Ruggero 
Published: June 2007

AbstractWe propose a set theory, called NRFST, in which the Cantorian axiom of infinity is negated, and a new notion of infinity is introduced via non standard methods, i. e. via adequate notions of standard and internal, two unary predicates added to the language of ZF. After some initial results on NRFST, we investigate its relative consistency with respect to ZF and Kawai's WNST.
Binary Relations and Permutation Groups
Authors: Andréka Hajnal , Düntsch Ivo 
Published: June 2007

AbstractWe discuss some new properties of the natural Galois connection among set relation algebras, permutation groups, and first order logic. In particular, we exhibit infinitely many permutational relation algebras without a Galois closed representation, and we also show that every relation algebra on a set with at most six elements is Galois closed and essentially unique. Thus, we obtain the surprising result that on such sets, logic with three variables is as powerful in expression as full first order logic.
Well‐Defined Fuzzy Sentential Logic
Authors: Turunen Esko 
Published: June 2007

AbstractA many‐valued sentential logic with truth values in an injective MV‐algebra is introduced and the axiomatizability of this logic is proved. The paper develops some ideas of Goguen and generalizes the results of Pavelka on the unit interval. The proof for completeness is purely algebraic. A corollary of the Completeness Theorem is that fuzzy logic on the unit interval is semantically complete if and only if the algebra of the truth values is a complete MV‐algebra. In the well‐defined fuzzy sentential logic holds the Compactness Theorem, while the Deduction Theorem and the Finiteness Theorem in general do not hold. Because of its generality and good‐behaviour, MV‐valued logic can be regarded as a mathematical basis of fuzzy reasoning.