bluuebunny/crossref_metadata_2025_split huggingface dataset:
On finite approximations of topological algebraic systems
Authors: Glebsky L. Yu. , Gordon E. I. , Henson C. Ward 
Published: December 2007

AbstractWe introduce and discuss a concept of approximation of a topological algebraic systemAby finite algebraic systems from a given class. IfAis discrete, this concept agrees with the familiar notion of alocal embeddingofAin a classof algebraic systems. One characterization of this concept states thatAis locally embedded iniff it is a subsystem of an ultraproduct of systems from. In this paper we obtain a similar characterization of approximability of a locally compact systemAby systems fromusing the language of nonstandard analysis.In the signature ofAwe introducepositive boundedformulas and theirapproximations;these are similar to those introduced by Henson [14] for Banach space structures (see also [15, 16]). We prove that a positive bounded formula φ holds inAif and only if all precise enough approximations of φ hold in all precise enough approximations ofA.We also prove that a locally compact field cannot be approximated arbitrarily closely by finite (associative) rings (even if the rings are allowed to be non-commutative). Finite approximations of the field ℝ can be considered as possible computer systems for real arithmetic. Thus, our results show that there do not exist arbitrarily accurate computer arithmetics for the reals that are associative rings.
Type-definable and invariant groups in o-minimal structures
Authors: Maříková Jana 
Published: December 2007

AbstractLet M be a big o-minimal structure and G a type-definable group in Mn. We show that G is a type-definable subset of a definable manifold in Mn that induces on G a group topology. If M is an o-minimal expansion of a real closed field, then G with this group topology is even definably isomorphic to a type-definable group in some Mk with the topology induced by Mk. Part of this result holds for the wider class of so-called invariant groups: each invariant group G in Mn has a unique topology making it a topological group and inducing the same topology on a large invariant subset of the group as Mn.
Non-branching degrees in the Medvedev lattice of Π10 classes
Authors: Alfeld Christopher P. 
Published: December 2007

AbstractA class is the set of paths through a computable tree. Given classes P and Q, P is Medvedev reducible to Q, P ≤MQ, if there is a computably continuous functional mapping Q into P. We look at the lattice formed by subclasses of 2ω under this reduction. It is known that the degree of a splitting class of c.e. sets is non-branching. We further characterize non-branching degrees, providing two additional properties which guarantee non-branching: inseparable and hyperinseparable. Our main result is to show that non-branching iff inseparable if hyperinseparable if homogeneous and that all unstated implications do not hold. We also show that inseparable and not hyperinseparable degrees are downward dense.
A question of van den Dries and a theorem of Lipshitz and Robinson; Not everything is standard
Authors: Hrushovski Ehud , Peterzil Ya'acov 
Published: December 2007

AbstractWe use a new construction of an o-minimal structure, due to Lipshitz and Robinson, to answer a question of van den Dries regarding the relationship between arbitrary o-minimal expansions of real closed fields and structures over the real numbers. We write a first order sentence which is true in the Lipshitz-Robinson structure but fails in any possible interpretation over the field of real numbers.
Completeness of MLL proof-nets w.r.t. weak distributivity
Authors: Joinet Jean-Baptiste 
Published: December 2007

AbstractWe examine ‘weak-distributivity’ as a rewriting rule defined on multiplicative proofstructures (so, in particular, on multiplicative proof-nets: MLL). This rewriting does not preserve the type of proof-nets, but does nevertheless preserve their correctness. The specific contribution of this paper, is to give a direct proof of completeness for : starting from a set of simple generators (proof-nets which are a n-ary ⊗ of Ց-ized axioms), any mono-conclusion MLL proof-net can be reached by rewriting (up to ⊗ and Ց associativity and commutativity).
The logic of interactive turing reduction
Authors: Japaridze Giorgi 
Published: December 2007

AbstractThe paper gives a soundness and completeness proof for the implicative fragment of intuitionistic calculus with respect to the semantics of computability logic, which understands intuitionistic implication as interactive algorithmic reduction. This concept — more precisely, the associated concept of reducibility — is a generalization of Turing reducibility from the traditional, input/output sorts of problems to computational tasks of arbitrary degrees of interactivity.
Simplicial structures in MV-algebras and logic
Authors: Belluce L. P. , Di Nola A. 
Published: December 2007

Classical logic, as is well known, can be analyzed in a great part by algebraic methods using the Lindenbaum algebra obtained from the formal system. For example the completeness theorem for this logic becomes equivalent to the semisimplicity of the obtained Lindenbaum algebra.Since Chang [4, 5], Łukasiewicz logic has also been analyzed algebraically through the associated Lindenbaum type algebra, that is the algebra of equivalence classes obtained from the relation of provable equivalence. In this case this algebra is an MV-algebra [4]. Once again logical notions have an algebraic counterpart, for example, completeness relates strongly to semisimplicity [4, 5]. However, unlike the classical case where the algebras in question are Boolean and always semisimple, not all MV-algebras are semisimple. This fact, in a sense, enriches the theory of MV-algebras.Now every MV-algebra can be considered a Lindenbaum type algebra, namely an algebra associated to Łukasiewicz logic with additional axioms. Thus we can carry over to any MV-algebra various logical notions such as (in) completeness, consistency, satisfiability, etc.Two important logical notions are those of “formal consequence” and “semantical consequence”. The former just says that a wff α is deducible from a set of wff via the axioms and rules of inference, while the latter just says that every evaluation that “satisfies” all the members of also “satisfies” α.Informally call these relations F, S respectively; consider them as binary relations, Fα and Sα.Now the completeness theorem just states F = S. Thus we can talk about an MV-algebra being “complete” provided the associated relations F, S are equal.
Successor-invariant first-order logic on finite structures
Authors: Rossman Benjamin 
Published: December 2007

AbstractWe consider successor-invariant first-order logic (FO + succ)inv, consisting of sentences Φ involving an “auxiliary” binary relation S such that (, S1) ⊨ Φ ⇔ (, S2) ⊨ Φ for all finite structures and successor relations S1, S2 on . A successor-invariant sentence Φ has a well-defined semantics on finite structures with no given successor relation: one simply evaluates Φ on (, S) for an arbitrary choice of successor relation S. In this article, we prove that (FO + succ)inv is more expressive on finite structures than first-order logic without a successor relation. This extends similar results for order-invariant logic [8] and epsilon-invariant logic [10].
Which structural rules admit cut elimination? An algebraic criterion
Authors: Terui Kazushige 
Published: December 2007

AbstractConsider a general class of structural inference rules such as exchange, weakening, contraction and their generalizations. Among them, some are harmless but others do harm to cut elimination. Hence it is natural to ask under which condition cut elimination is preserved when a set of structural rules is added to a structure-free logic. The aim of this work is to give such a condition by using algebraic semantics.We consider full Lambek calculus (FL), i.e., intuitionistic logic without any structural rules, as our basic framework. Residuated lattices are the algebraic structures corresponding to FL. In this setting, we introduce a criterion, called the propagation property, that can be stated both in syntactic and algebraic terminologies. We then show that, for any set ℛ of structural rules, the cut elimination theorem holds for FL enriched with ℛ if and only if ℛ satisfies the propagation property.As an application, we show that any set ℛ of structural rules can be “completed” into another set ℛ*, so that the cut elimination theorem holds for FL enriched with ℛ*. while the provability remains the same.
Models of non-well-founded sets via an indexed final coalgebra theorem
Authors: van den Berg Benno , de Marchi Federico 
Published: December 2007

AbstractThe paper uses the formalism of indexed categories to recover the proof of a standard final coalgebra theorem, thus showing existence of final coalgebras for a special class of functors on finitely complete and cocomplete categories. As an instance of this result, we build the final coalgebra for the powerclass functor, in the context of a Heyting pretopos with a class of small maps. This is then proved to provide models for various non-well-founded set theories, depending on the chosen axiomatisation for the class of small maps.
Some results in polychromatic Ramsey theory
Authors: Abraham Uri , Cummings James , Smyth Clifford 
Published: December 2007

Classical Ramsey theory(at least in its simplest form) is concerned with problems of the following kind: given a setXand a colouring of the set[X]nof unorderedn-tuples fromX, find a subsetY ⊆ Xsuch that all elements of[Y]nget the same colour. Subsets with this property are calledmonochromaticorhomogeneous, and a typical positive result in Ramsey theory has the form that whenXis large enough and the number of colours is small enough we can expect to find reasonably large monochromatic sets.Polychromatic Ramsey theoryis concerned with a “dual” problem, in which we are given a colouring of[X]nand are looking for subsetsY ⊆ Xsuch that any two distinct elements of[Y]ngetdifferentcolours. Subsets with this property are calledpolychromaticorrainbow. Naturally if we are looking for rainbow subsets then our task becomes easier when there are many colours. In particular given an integerkwe say that a colouring isk-boundedwhen each colour is used for at mostkmanyn-tuples.At this point it will be convenient to introduce a compact notation for stating results in polychromatic Ramsey theory. We recall that in classical Ramsey theory we writeto mean “every colouring of[κ]ninkcolours has a monochromatic set of order type α”. We will writeto mean “everyk-bounded colouring of[κ]nhas a polychromatic set of order type α”. We note that whenκis infinite andkis finite ak-bounded colouring will use exactlyκcolours, so we may as well assume thatκis the set of colours used.
Lower bounds for modal logics
Authors: Hrubeš Pavel 
Published: December 2007

AbstractWe give an exponential lower bound on number of proof-lines in the proof system K of modal logic, i.e., we give an example of K-tautologies ψ1, ψ2, … s.t. every K-proof of ψi must have a number of proof-lines exponential in terms of the size of ψi. The result extends, for the same sequence of K-tautologies, to the systems K4, Gödel–Löb's logic, S andS4. We also determine some speed-up relations between different systems of modal logic on formulas of modal-depth one.
Computable embeddings and strongly minimal theories
Authors: Chisholm J. , Knight J. F. , Miller S. 
Published: December 2007

AbstractHere we prove that if T and T′ are strongly minimal theories, where T′ satisfies a certain property related to triviality and T does not, and T′ is model complete, then there is no computable embedding of Mod(T) into Mod(T′). Using this, we answer a question from [4], showing that there is no computable embedding of VS into ZS, where VS is the class of infinite vector spaces over ℚ, and ZS is the class of models of Th(ℤ, S). Similarly, we show that there is no computable embedding of ACF into ZS, where ACF is the class of algebraically closed fields of characteristic 0.
Psychopathology and Clinical Features in an Italian Sample of Patients with Myofascial and Temporomandibular Joint Pain: Preliminary Data
Authors: Nifosi F. , Violato E. , Pavan C. , Sifari L. , Novello G. , Nardini L. Guarda , Manfredini D. , Semenzin M. , Pavan L. , Marini M. 
Published: December 2007

Objective: Aim of this study was to provide data on the relationships between psychopathological variables and temporomandibular disorders (TMD). Sixty-three TMD patients were investigated using clinical and anamnestical psychiatric informations and psychopathological measures. Methods: Three groups of TMD patients were recruited according to the Research Diagnostic Criteria for TMD guidelines: a group of patients presenting myofascial pain alone (RDC/TMD axis I group I), a group with temporomandibular joint (TMJ) pain alone (RDC/TMD axis I group IIIa, IIIb), and a group presenting both myofascial and TMJ pain. Two secondary groups were identified on the basis of the presence/absence of myofascial pain. The study design provided a psychiatric interview and psychometric assessment including the Symptom Check List-90-Revised (SCL-90-R), the Hamilton Depression Rating Scale (HDRS), and the Hamilton Anxiety Rating Scale (HARS). Results: -Psychiatric evaluation: Myofascial pain patients had higher scores for personal psychiatric history and a history of more frequent psychotropic drug use. -HDRS and HARS: The sample presented scores indicating mild depressive symptoms and moderate anxiety symptoms. -SCL-90-R: The global sample showed acute levels of psychological distress as measured by the GSI score (Global Severity Index). Myofascial pain patients scored higher than TMJ pain patients in the GSI ( p = .028), PAR (paranoia; p = .015), PSY (psychoticism; p = .032), and HOS (hostility; p = .034) subscales. Conclusions: TMD patients showed elevated levels of depression, somatization, and anxiety. These characteristics did not differ significantly between patients with myofascial or TMJ pain. Other specific psychopathological dimensions, detected with SCL-90-R, appeared to be closely associated to the myofascial component.
Primary Care Physicians' Discussion of Emotional Distress and Patient Satisfaction
Authors: Gross Revital , Brammli-Greenberg Shuli , Tabenkin Hava , Benbassat Jochanan 
Published: December 2007

Objectives: To assess: a) the prevalence and determinants of self-reported emotional distress in the Israeli population; b) the rate of self-reported discussion of emotional distress with family physicians; and c) the association between such discussions and patient satisfaction with care. Method: Design: Retrospective, cross-sectional survey that was conducted through structured telephone interviews in Hebrew, Arabic, and Russian. This study was part of a larger study assessing patients' perceptions of the quality of health services. Participants: A representative sample of 1,849 Israeli citizens aged 22 to 93 (response rate: 84%). Independent variables: Gender, age, ethnicity (spoken language), education, income, self-reported chronic disease, self-reported episode(s) of emotional distress during the last year, and having discussed emotional distress with the family physician. Outcome measure: satisfaction with care. Results: 28.4% reported emotional distress and 12.5% reported discussion of emotional distress with a primary care physician in the past year. Logistic regression identified female gender, Arab ethnicity, low income, and chronic illness as independent correlates of emotional distress. These as well as Russian speakers and having experienced emotional distress during the past year were identified as independent correlates of discussion of emotional distress with the family physician. Patients who reported discussion of emotional distress with their family physician were significantly more satisfied with care. Conclusions: Encouraging physicians to detect and discuss emotional distress with their patients may increase patient satisfaction with care, and possibly also improve patients' well-being and reduce health care costs.
A comparative seasonal pollution assessment study on Ennore Estuary with respect to metal accumulation in the grey mullet, Mugil cephalus
Authors: Padmini E. , Geetha B. 
Published: December 2007

Abstract
Environmental pollution is currently a major concern due to unorganised and increased industrialization and urban development. In the Tamilnadu state of India, on the Bay of Bengal, lies the Ennore estuary, which is an important industrial centre. The main industries in the region include a fertilizer company, refineries, a rubber factory, paint industry and a thermal power station. Investigations into the seasonal pollution impacts on the distribution of various metals in the waters of the Ennore estuary, situated in North Chennai, Tamilnadu, India, and the concentrations of some of the toxic metals in the tissue of the grey mullet, Mugil cephalus L., inhabiting in the same estuary were conducted during the period of April 2004 to March 2006.
The results were compared to those of the Kovalam estuary, which is unpolluted. In the water at one sample site of the Ennore estuary, heavy metal concentrations ranged between: Pb 0.15-0.23, Hg 0.05-0.06, Cd 0.01-0.03, and Cr 3.33-1.093 ppm for summer and monsoon seasons, and were significantly related to the seasonal rains (p<0.01). In contrast, heavy metal concentrations in the Kovalam estuary ranged between: Pb 0.043-0.039, Hg non-detectable-0.001, Cd 0.01-0.098, and Cr 0.063-0.052 ppm, and were not significantly related to the rainy season. The metal concentrations found in the muscle tissues of Mugil cephalus L., at the same site on the Ennore estuary were: Fe 11.06 ±0.29, Zn 1.67 ±0.14, Cr 2.98 ±0.15, and Pb 1.26 ±0.11 ppm, which were also significantly related to season (p<0.01). The metal concentrations in fish inhabiting the Kovalam estuary were: Fe 2.17 ±0.15, Zn 0.42 ±0.05, Cr 0.63 ±0.04, and Pb 0.31 ±0.04, and showed no significant seasonal difference. The highest metal concentrations found in the tissues of the Ennore estuary fish which lead to the oxidative stress and shorten the lifespan of the fish are postulated to primarily result from anthropogenic activities and effluent discharge from the local industrial activities.
Osseous cyst‐like lesions in the feet of lame horses: Diagnosis by standing low‐field magnetic resonance imaging
Authors: Mair T. S. , Sherlock C. E. 
Published: December 2007

SummaryOsseous cyst‐like lesions (OCLLs) were diagnosed by standing low‐field magnetic resonance (MR) imaging in 9 mature horses (age range 6–17 years). All horses had been subjected to a routine lameness evaluation (including standard foot radiographs) with no diagnosis being reached prior to MR imaging. The duration of lameness ranged from one month to one year. OCLLs were diagnosed in 12 feet. The site of the lesions included the distal phalanx in 11 feet (subchondral bone in 4, insertion of collateral ligaments of the distal interphalangeal joint in 4, insertion of the distal sesamoidean impar ligament in 3) and the subchondral bone of the distal aspect of the middle phalanx in one foot. OCLLs were characterised by discrete spherical or elliptical areas of high or intermediate signal in all MR sequences. In most cases the lesion was surrounded by a rim of bone with abnormally low signal.
Structural control of englacial drainage systems in Himalayan debris-covered glaciers
Authors: Gulley J. , Benn D.I. 
Published: December 2007

AbstractEnglacial cave systems were mapped using speleological techniques in three debris-covered glaciers in the Khumbu Himal, Nepal. Detailed three-dimensional mapping of the cave systems and observations of relationships with structures in the surrounding ice show conduits formed by a mechanism directly analogous to speleogenesis in limestone karst. The highest, oldest parts of all passages developed along debris-filled crevasse traces with hydraulic conductivity in the range 10–4 to 10–5ms–1. Conduits form when these hydraulically efficient pathways bridge between areas with different hydraulic potential. They then evolve by grading (through head-ward migration of nick points and vertical incision) to local base level, often the surface of supraglacial lakes. Most supraglacial lakes on Himalayan glaciers are perched above the elevation of the terminal stream, and exist for a few years before draining through englacial conduits. As a result, near-surface drainage evolution is frequently interrupted by base-level fall, and conduits may record multiple phases of incision. Conduits commonly migrate laterally during incision, undermining higher levels of the ice and encouraging collapse. Voids can be created by fluvial processes and collapse of crevassed ice. The oft-noted resemblance of the surface morphology of debris-covered glaciers to karst landscapes thus extends to the subsurface, and karst hydrology provides a framework for understanding englacial drainage.
Exact solutions to the thermomechanically coupled shallow-ice approximation: effective tools for verification
Authors: Bueler Ed , Brown Jed , Lingle Craig 
Published: December 2007

AbstractWe describe exact solutions to the thermomechanically coupled shallow-ice approximation in three spatial dimensions. Although artificially constructed, these solutions are very useful for testing numerical methods. In fact, they allow us to verify a finite-difference scheme, that is, to show that the results of our numerical scheme converge to the correct continuum values as the grid is refined in three dimensions. Comparison of numerical results with exact solutions has helped us to precisely quantify and understand some of the numerical errors we are making. Our verified numerical scheme shows the basal temperature spokes which arose in the EISMINT (European Ice Sheet Modelling INiTiative) II intercomparison (Payne and others, 2000). A careful analysis describes these warm spokes as numerical errors which occur when the derivative of the strain-heating term with respect to the temperature is large. On the other hand, the appearance of basal temperature spokes in a verified numerical scheme strongly suggests that they are a feature of the EISMINT II experiment F continuum problem. In fact, they are clear evidence of an unstable equilibrium point of the continuum problem. This paper is a sequel to Bueler and others (2005) which addresses exact solutions and verification in the isothermal case.
The general viscous relation for the response of ice and its implications in the reduced model for ice-sheet flow
Authors: Morland L.W. 
Published: December 2007

AbstractAnalyses of confined and unconfined compression combined with shear, and of biaxial stress laterally confined or unconfined, are presented for a general deviatoric viscous relation describing the response of an incompressible material. At present, numerical models for ice-sheet flow commonly adopt a very simple viscous law throughout the ice sheet, in which the deviatoric stress is coaxial with the strain rate, and the single response function depends on only one invariant, and is determined by single stress component tests which cannot verify the validity of the simplification. The analysis presented here is concerned with two-stress-component experimental configurations which could determine the general quadratic form of a viscous relation, with two response functions depending on two invariants. It is shown that the two combined compression and shear tests can also check the consistency of a viscous fluid assumption, but not so the biaxial stress tests. Each test allows a direct assessment of the significance of the quadratic term. It is then shown that a significant quadratic term changes the relative stress magnitudes in the commonly adopted reduced model for ice-sheet flow, and that the crucial simplifications are not achieved.