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Model Theory (model + theory)
Selected AbstractsLinear Model Theory: Univariate, Multivariate, and Mixed Models edited by Muller, K. E. and Stewart, P. W.BIOMETRICS, Issue 1 2007Article first published online: 16 APR 200 No abstract is available for this article. [source] A Causal Model Theory of the Meaning of Cause, Enable, and PreventCOGNITIVE SCIENCE - A MULTIDISCIPLINARY JOURNAL, Issue 1 2009Steven Sloman Abstract The verbs cause, enable, and prevent express beliefs about the way the world works. We offer a theory of their meaning in terms of the structure of those beliefs expressed using qualitative properties of causal models, a graphical framework for representing causal structure. We propose that these verbs refer to a causal model relevant to a discourse and that "A causes B" expresses the belief that the causal model includes a link from A to B. "A enables/allows B" entails that the model includes a link from A to B, that A represents a category of events necessary for B, and that an alternative cause of B exists. "A prevents B" entails that the model includes a link from A to B and that A reduces the likelihood of B. This theory is able to account for the results of four experiments as well as a variety of existing data on human reasoning. [source] Time in Language, Situation Models, and Mental SimulationsLANGUAGE LEARNING, Issue 2008Rolf A. Zwaan The purpose of this article is to propose a view of language processing, and particularly the role of aspect therein, from a mental-simulation perspective. I argue that situation model theories can account for the flow between and interconnectedness of event representations but that mental simulation theories are needed to account for the internal structure of event representations. The article concludes with some speculative thoughts on how simulation theories might accomplish this intellectual feat. [source] An Experimental Investigation of Approaches to Audit Decision Making: An Evaluation Using Systems-Mediated Mental Models,CONTEMPORARY ACCOUNTING RESEARCH, Issue 2 2005AMY K. CHOY Abstract The objective of this research is to articulate a decision-making foundation for the systems audit approach. Under this audit approach, the auditor first gains an understanding of the auditee's economic environment, strategy, and business processes and then forms expectations about its performance and financial reporting. Proponents of this audit approach argue that decision making is enhanced because the knowledge of the system allows the auditor to focus on the most important risks. However, there has not been an explicit framework to explain how systems knowledge can enhance decision making. To provide such a framework, we combine mental model theory with general systems theory to produce a hypothesis we refer to as a systems-mediated mental model hypothesis. We test this hypothesis using experimental economics methods. We find that (1) subjects make systematic errors under the setting without an organizing framework provided by the systems information, and (2) the presence of an organizing framework results in lower reporting errors. Importantly, the organizing framework significantly enhances decision making in the settings where the environment changed. Establishing a decision-making foundation for systems audits can provide an important building block that, in part, can contribute to the development of a more effective and efficient audit technology - an important objective now when audits are facing a credibility crisis. [source] Generalized marker regression and interval QTL mapping methods for binary traits in half-sib family designsJOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 5 2001H. N. Kadarmideen A Generalized Marker Regression Mapping (GMR) approach was developed for mapping Quantitative Trait Loci (QTL) affecting binary polygenic traits in a single-family half-sib design. The GMR is based on threshold-liability model theory and regression of offspring phenotype on expected marker genotypes at flanking marker loci. Using simulation, statistical power and bias of QTL mapping for binary traits by GMR was compared with full QTL interval mapping based on a threshold model (GIM) and with a linear marker regression mapping method (LMR). Empirical significance threshold values, power and estimates of QTL location and effect were identical for GIM and GMR when QTL mapping was restricted to within the marker interval. These results show that the theory of the marker regression method for QTL mapping is also applicable to binary traits and possibly for traits with other non-normal distributions. The linear and threshold models based on marker regression (LMR and GMR) also resulted in similar estimates and power for large progeny group sizes, indicating that LMR can be used for binary data for balanced designs with large families, as this method is computationally simpler than GMR. GMR may have a greater potential than LMR for QTL mapping for binary traits in complex situations such as QTL mapping with complex pedigrees, random models and models with interactions. Generalisierte Marker Regression und Intervall QTL Kartierungsmethoden für binäre Merkmale in einem Halbgeschwisterdesign Es wurde ein Ansatz zur generalisierten Marker Regressions Kartierung (GMR) entwickelt, um quantitative Merkmalsloci (QTL) zu kartieren, die binäre polygenetische Merkmale in einem Einfamilien-Halbgeschwisterdesign beeinflussen. Das GMR basiert auf der Theorie eines Schwellenwertmodells und auf der Regression des Nachkommenphänotyps auf den erwarteten Markergenotyp der flankierenden Markerloci. Mittels Simulation wurde die statistische Power und Schiefe der QTL Kartierung für binäre Merkmale nach GMR verglichen mit vollständiger QTL Intervallkartierung, die auf einem Schwellenmodell (GIM) basiert, und mit einer Methode zur linearen Marker Regressions Kartierung (LMR). Empirische Signifikanzschwellenwerte, Power und Schätzer für die QTL Lokation und der Effekt waren für GIM und GMR identisch, so lange die QTL Kartierung innerhalb des Markerintervalls definiert war. Diese Ergebnisse zeigen, dass die Theorie der Marker Regressions-Methode zur QTL Kartierung auch für binäre Merkmale und möglicherweise auch für Merkmale, die keiner Normalverteilung folgen, geeignet ist. Die linearen und Schwellenmodelle, die auf Marker Regression (LMR und GMR) basieren, ergaben ebenfalls ähnliche Schätzer und Power bei großen Nachkommengruppen, was schlussfolgern lässt, dass LMR für binäre Daten in einem balancierten Design mit großen Familien genutzt werden kann. Schließlich ist diese Methode computertechnisch einfacher als GMR. GMR mag für die QTL Kartierung bei binären Merkmalen in komplexen Situationen ein größeres Potential haben als LMR. Ein Beispiel dafür ist die QTL Kartierung mit komplexen Pedigrees, zufälligen Modellen und Interaktionsmodellen. [source] Constructive and Classical Models for Results in Economics and Game TheoryMETROECONOMICA, Issue 2-3 2004Kislaya Prasad ABSTRACT A standard approach in economic theory is to use a formal language to prove results about an economy or a game. In this paper, model theory is used to examine interpretations of such results. The particular focus is on constructive theorems, since results established by constructive methods are valid for many different interpretations, whereas classical theorems are valid more narrowly. I discuss why non-classical models may be of interest and also describe applications of model theory to economics in classical contexts, e.g. non-standard analysis. The paper advocates a viewpoint suggesting that constructive models are tools for studying worlds in which agents' knowledge of the world is incomplete. [source] A new technique for proving realisability and consistency theorems using finite paraconsistent models of cut-free logicMLQ- MATHEMATICAL LOGIC QUARTERLY, Issue 6 2006Arief Daynes Abstract A new technique for proving realisability results is presented, and is illustrated in detail for the simple case of arithmetic minus induction. CL is a Gentzen formulation of classical logic. CPQ is CL minus the Cut Rule. The basic proof theory and model theory of CPQ and CL is developed. For the semantics presented CPQ is a paraconsistent logic, i.e. there are non-trivial CPQ models in which some sentences are both true and false. Two systems of arithmetic minus induction are introduced, CL-A and CPQ-A based on CL and CPQ, respectively. The realisability theorem for CPQ-A is proved: It is shown constructively that to each theorem A of CPQ-A there is a formula A *, a so-called "realised disjunctive form of A ", such that variables bound by essentially existential quantifiers in A * can be written as recursive functions of free variables and variables bound by essentially universal quantifiers. Realisability is then applied to prove the consistency of CL-A, making use of certain finite non-trivial inconsistent models of CPQ-A. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Omitting types in fuzzy logic with evaluated syntaxMLQ- MATHEMATICAL LOGIC QUARTERLY, Issue 3 2006Petra Murinová Abstract This paper is a contribution to the development of model theory of fuzzy logic in narrow sense. We consider a formal system Ev, of fuzzy logic that has evaluated syntax, i. e. axioms need not be fully convincing and so, they form a fuzzy set only. Consequently, formulas are provable in some general degree. A generalization of Gödel's completeness theorem does hold in Ev,. The truth values form an MV-algebra that is either finite or ,ukasiewicz algebra on [0, 1]. The classical omitting types theorem states that given a formal theory T and a set ,(x1, , , xn ) of formulas with the same free variables, we can construct a model of T which omits ,, i. e. there is always a formula from , not true in it. In this paper, we generalize this theorem for Ev,, that is, we prove that if T is a fuzzy theory and ,(x1, , , xn ) forms a fuzzy set , then a model omitting , also exists. We will prove this theorem for two essential cases of Ev,: either Ev, has logical (truth) constants for all truth values, or it has these constants for truth values from [0, 1] , , only. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] G, -pieces of canonical partitions of G -spacesMLQ- MATHEMATICAL LOGIC QUARTERLY, Issue 5 2005Barbara Majcher-Iwanow Abstract Generalizing model companions from model theory we define companions of pieces of canonical partitions of Polish G -spaces. This unifies several constructions from logic. The central problem of the paper is the existence of companions which form a G -orbit which is a G, -set. We describe companions of some typical G -spaces. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] On topological properties of ultraproducts of finite setsMLQ- MATHEMATICAL LOGIC QUARTERLY, Issue 3 2005Gábor Sági Abstract In [3] a certain family of topological spaces was introduced on ultraproducts. These spaces have been called ultratopologies and their definition was motivated by model theory of higher order logics. Ultratopologies provide a natural extra topological structure for ultraproducts. Using this extra structure in [3] some preservation and characterization theorems were obtained for higher order logics. The purely topological properties of ultratopologies seem interesting on their own right. We started to study these properties in [2], where some questions remained open. Here we present the solutions of two such problems. More concretely we show 1. that there are sequences of finite sets of pairwise different cardinalities such that in their certain ultraproducts there are homeomorphic ultratopologies and 2. if A is an infinite ultraproduct of finite sets, then every ultratopology on A contains a dense subset D such that |D| < |A|. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Modelling of reserve carbohydrate dynamics, regrowth and nodulation in a N2 -fixing tree managed by periodic pruningsPLANT CELL & ENVIRONMENT, Issue 10 2000F. Berninger ABSTRACT We used a modified transport resistance approach to model legume tree growth, nodulation and dynamics of reserve carbohydrates after pruning. The model distributes growth between roots and shoots applying the transport resistance approach. Within shoots, growth is divided into leaves, branches and stems applying the pipe model theory. The model also accounts for the metabolic differences of principal N sources, nitrate, ammonium and atmospheric dinitrogen, in a mechanistic way. We compared the simulation results with measured biomass dynamics of Gliricidia sepium (Jacq.) Walp. (Papilionaceae: Robinieae) under humid and subhumid tropical conditions. Comparison showed that the biomass production predicted by the model is close to measured values. Total N2 fixation is also similar to measured values. Qualitatively the model increases the proportion of N2 fixation if roots acquire less mineral N. In the present study, the general form of the model is discussed and compared with similar models. The results encourage the use of this approach for studying biomass dynamics of legume trees under the scheme of periodic prunings. Also, it shows that process-based models have potential in the simulation of trees disturbed by prunings, herbivory or similar factors. [source] TWO ARGUMENTS AGAINST REALISMTHE PHILOSOPHICAL QUARTERLY, Issue 231 2008Timothy Bays I present two generalizations of Putnam's model-theoretic argument against realism. The first replaces Putnam's model theory with some new, and substantially simpler, model theory, while the second replaces Putnam's model theory with some more accessible results from astronomy. By design, both of these new arguments fail. But the similarities between these new arguments and Putnam's original arguments illuminate the latter's overall structure, and the flaws in these new arguments highlight the corresponding flaws in Putnam's arguments. [source] | |||||||||||||