In defense of base contraction

In the most common approaches to belief dynamics, states of belief are represented by sets that are closed under logical consequence. In an alternative approach, they are represented by non-closed belief bases. This representation has attractive properties not shared by closed representations. Most importantly, it can account for repeated belief changes that have not yet been satisfactorily accounted for in the closed approach.     

Multiple and iterated contraction reduced to single-step single-sentence contraction

Multiple contraction (simultaneous contraction by several sentences) and iterated contraction are investigated in the framework of specified meet contraction (s.m.c.) that is extended for this purpose. Multiple contraction is axiomatized, and so is finitely multiple contraction (contraction by a finite set of sentences). Two ways to reduce finitely multiple contraction to contraction by single sentences are introduced. The reduced operations are axiomatically characterized and their properties are investigated. Furthermore, it is shown how iterated contraction can be reduced to single-step, single-sentence contraction. However, in this framework the outcome of iterated contraction depends unavoidably on the order in which the inputs are received. This order-dependence makes it impossible to treat two inputs on an equal footing. Therefore it is often preferable to perform changes involving several pieces of information as multiple rather than iterated change.     

学习环境、成就目标定向对学业情绪和学业成就的影响:基于物理学科的研究

以733名中学生为被试,采用结构方程模型对物理环境目标结构、成就目标定向、物理学业情绪及物理学业成就的关系建构模型.结果发现:(1)物理环境掌握目标结构对积极高唤醒、积极低唤醒和消极高唤醒学业情绪皆有显著积极预测作用,而物理环境表现目标结构则只对消极高唤醒和消极低唤醒物理学业情绪有显著积极预测作用;(2)通过成就目标定向中介对物理学业情绪的影响效果,物理学业情绪在成就目标和物理学业成就之间起中介作用,但影响模式不同;(3)研究结果支持学业情绪控制-价值扩展模型.     

The Theory of Positive Disintegration through the Lens of Complexity Science

The article introduces the main ideas and concepts of D?browski’s theory of positive disintegration, and then subsequently provides a reconceptualization of this theory by complexity science. According to D?browski, positive disintegration is the mental development described by the process of transition from lower to higher levels of mental life and is stimulated by tension, inner conflict, struggle, and anxiety. This process can be modeled by a sequence of attractors (levels) as a control parameter (a developmental potential) changes and by a process of symmetry breaking. As an application of this theory, a conceptual model of adolescent development is presented.     

The Revision and Expansion of Self‐Theory through Preparedness

The present paper examines the psychological pathways by which accumulating experiences of possible self‐revision ultimately lead to revision of the core selves that define a broader personal narrative. In so doing, we expand the notion of naïve ‘self‐theories’ by identifying self‐serving attributions and possible selves as critical components that extend or undermine the core self‐theories of a unique personal narrative written (and revised) over a lifetime. Ultimately, we advance preparedness as the motivational force that drives the road from possible to core self‐revision over time.     

Pick Your Poison: Examining Adolescent Substance Use through Opportunity Theory

The present study examines substance use behaviors of middle and high school students, focusing on how varying influences of opportunity measures impact use of specific types of substances. The data used in the present study come from almost 4,000 students within 89 school contexts from students attending public school in a Southern state. Hierarchical logistic modeling is used to explore the influence of various opportunities at both the student and school levels on the use of different types of substances. Results indicate measures of opportunity at both the student and school levels were significant; however, measures at the individual level were consistently more influential.     

Maximal and perimaximal contraction

Generalizations of partial meet contraction are introduced that start out from the observation that only some of the logically closed subsets of the original belief set are at all viable as contraction outcomes. Belief contraction should proceed by selection among these viable options. Several contraction operators that are based on such selection mechanisms are introduced and then axiomatically characterized. These constructions are more general than the belief base approach. It is shown that partial meet contraction is exactly characterized by adding to one of these constructions the condition that all logically closed subsets of the belief set can be obtained as the outcome of a single (multiple) contraction. Examples are provided showing the counter-intuitive consequences of that condition, thus confirming the credibility of the proposed generalization of the AGM framework.     

Belief contraction without recovery

The postulate of recovery is commonly regarded to be the intuitively least compelling of the six basic Gärdenfors postulates for belief contraction. We replace recovery by the seemingly much weaker postulate of core-retainment, which ensures that if x is excluded from K when p is contracted, then x plays some role for the fact that K implies p. Surprisingly enough, core-retainment together with four of the other Gärdenfors postulates implies recovery for logically closed belief sets. Reasonable contraction operators without recovery do not seem to be possible for such sets. Instead, however, they can be obtained for non-closed belief bases. Some results on partial meet contractions on belief bases are given, including an axiomatic characterization and a non-vacuous extension of the AGM closure condition.     

How to bereally contraction free

A logic is said to becontraction free if the rule fromA (A B) toA B is not truth preserving. It is well known that a logic has to be contraction free for it to support a non-trivial naïve theory of sets or of truth. What is not so well known is that if there isanother contracting implication expressible in the language, the logic still cannot support such a naïve theory. A logic is said to berobustly contraction free if there is no such operator expressible in its language. We show that a large class of finitely valued logics are each not robustly contraction free, and demonstrate that some other contraction free logics fail to be robustly contraction free. Finally, the sublogics of (with the standard connectives) are shown to be robustly contraction free.     

从系统论的角度看系统性红斑狼疮分类标准的变迁

系统性红斑狼疮是一种复杂的自身免疫性疾病,本文试从系统论中的整体性、层次性、动态性、目的性原理来阐述SLE分类标准的变迁,揭示系统性思维对于正确把握SLE分类标准的重要性,临床诊疗决策中系统论的运用具有重要意义.     

Apparent contraction of edge angles.

The corner effect, the Münsterberg illusion, and the Café Wall illusion are explained by a model postulating that the corner effect is an orientation illusion specific to corner edges and that the perceived orientations of these edges are shifted toward angle contraction. It is also assumed that the effect is greatest when the corner edges show the same or similar edge contrast at the corner. This model yields three new types of illusions: the 'checkered illusion', the 'illusion of shifted gradations', and the 'illusion of striped cords'. Each of them gives many variations making a three-dimensional impression.     

Merging the Self-Determination Theory and the Broaden and Build Theory through the nexus of positive affect: A macro theory of positive functioning

The Macro Theory of Positive Functioning integrates key aspects of the Self-Determination Theory and the Broaden and Build Theory. The theory posits a model that provides new perspectives on the development of positive characteristics. The Macro Theory proposes that higher levels of intrinsic motivation and basic needs satisfaction as described by the Self-Determination Theory result in high levels of positive affect (consisting of emotions such as joy). The Broaden and Build Theory proposes that high levels of positive affect result in a broadening of perspective resulting in more engagement with opportunities and relationships, which builds beneficial cognitive and behavioural resources and skills. Such resources and skills may manifest as positive characteristics described and studied in the positive psychology approach. These characteristics include self-compassion, self-efficacy, empathy, emotional intelligence, and character strengths. High levels of these characteristics may result in optimal functioning. Results from model testing with concurrent data designs as well as experimental designs provide initial support for the Macro Theory.     

The Productive Power of Ambiguity: Rethinking Homosexuality through the Virtual and Developmental Systems Theory

This paper juxtaposes Deleuze's notion of the virtual alongside Oyama's notion of a developmental system in order to explore the promises and perils of thinking bodily identity as indeterminate at a time when new technologies render bodily ambiguity increasingly productive of both economic profit and power relations.     

On structural contraction and why it fails

Synthese - The goal of the paper is to discuss whether substructural non-contractive accounts of the truth-theoretic paradoxes can be philosophically motivated. First, I consider a number of...     

Lambek calculus with restricted contraction and expansion

This paper deals with some strengthenings of the non-directional product-free Lambek calculus by means of additional structural rules. In fact, the rules contraction and expansion are restricted to basic types. For each of the presented systems the usual proof-theoretic notions are discussed, some new concepts especially designed for these calculi are introduced reflecting their intermediate position between the weaker and the stronger sequent-systems.This work was supported by the Research Council of Slovenija     

Age-related EMG variables during maximum voluntary contraction

We studied the neuromuscular adaptation that occurs with aging by comparing changes in surface electromyography (EMG) variables from the tibialis anterior muscle in 12 young (21.4 +/- 1.7 yr. old) and 13 older subjects (70.8 +/- 3.1 yr. old). EMG variables such as the muscle fiber conduction velocity, median frequency, and averaged rectified value were calculated during maximum voluntary contraction for 5-sec. isometric contractions. The dorsiflexion force, muscle fiber conduction velocity, median frequency, and average rectified value during maximum voluntary contraction were significantly smaller in the older than in the younger group (p < .05). These results suggested that the neuromuscular system in older subjects is affected by the selective atrophy of fast twitch fibers and differences in motor unit firing statistics. Our results suggest the utility of applying the EMG observed during maximum voluntary contraction to the noninvasive evaluation of neuromuscular function in elderly persons.