Products of Modal Logics. Part 3: Products of Modal and Temporal Logics

In this paper we improve the results of [2] by proving the product f.m.p. for the product of minimal n-modal and minimal n-temporal logic. For this case we modify the finite depth method introduced in [1]. The main result is applied to identify new fragments of classical first-order logic and of the equational theory of relation algebras, that are decidable and have the finite model property.     

Recognition of natural scenes from global properties: seeing the forest without representing the trees

Human observers are able to rapidly and accurately categorize natural scenes, but the representation mediating this feat is still unknown. Here we propose a framework of rapid scene categorization that does not segment a scene into objects and instead uses a vocabulary of global, ecological properties that describe spatial and functional aspects of scene space (such as navigability or mean depth). In Experiment 1, we obtained ground truth rankings on global properties for use in Experiments 2-4. To what extent do human observers use global property information when rapidly categorizing natural scenes? In Experiment 2, we found that global property resemblance was a strong predictor of both false alarm rates and reaction times in a rapid scene categorization experiment. To what extent is global property information alone a sufficient predictor of rapid natural scene categorization? In Experiment 3, we found that the performance of a classifier representing only these properties is indistinguishable from human performance in a rapid scene categorization task in terms of both accuracy and false alarms. To what extent is this high predictability unique to a global property representation? In Experiment 4, we compared two models that represent scene object information to human categorization performance and found that these models had lower fidelity at representing the patterns of performance than the global property model. These results provide support for the hypothesis that rapid categorization of natural scenes may not be mediated primarily though objects and parts, but also through global properties of structure and affordance.     

Equivalents for a Quasivariety to be Generated by a Single Structure

We present some equivalent conditions for a quasivariety of structures to be generated by a single structure. The first such condition, called the embedding property was found by A.I. Mal′tsev in [6]. It says that if are nontrivial, then there exists such that A and B are embeddable into C. One of our equivalent conditions states that the set of quasi-identities valid in is closed under a certain Gentzen type rule which is due to J. Łoś and R. Suszko [5]. Presented by Jacek Malinowski     

Exploitation via labour power in Marx

Marx's account of capitalist exploitation is undermined by inter-related confusions surrounding the notion of labour power. These confusions relate to [i] what labour power is, [ii] what happens to labour power in the labour market, and [iii] what the epistemic status of labour power is (the issue of appearance and reality). The central theses of the paper are [a] that property ownership is the wrong model for understanding the exploitation of labour, and [b] that the concept of exploitation is linked more fruitfully to a conception of distributive injustice than to Marx's theory of surplus value.     

Should knowledge entail belief?

The appropriateness of S5 as a logic of knowledge has been attacked at some length in the philosophical literature. Here one particular attack based on the interplay between knowledge and belief is considered: Suppose that knowledge satisfies S5, belief satisfies KD45, and both the entailment property (knowledge implies belief) and positive certainty (if the agent believes something, she believes she knows it) hold. Then it can be shown that belief reduces to knowledge: it is impossible to have false beliefs. While the entialment property has typically been viewed as perhaps the least controversial of these assumptions, an argument is presented that it can plausibly be viewed as the culprit. More precisely, it is shown that this attack fails if we weaken the entailment property so that it applies only to objective (nonmodal) formulas, rather than to arbitrary formulas. Since the standard arguments in favor of the entailment property are typically given only for objective formulas, this observation suggests that care must be taken in applying intuitions that seem reasonable in the case of objective formulas to arbitrary formulas.Research sponsored in part by the Air Force office of Scientific Research (AFSC), under Contract F49620-91-C-0080. The United States Government is authorized to reproduce and distribute reprints for governmental purposes.     

短时距估计中的标量特性

使用单任务研究程序,采用预期式研究范式和再现时距的研究方法,从心理物理学的视角,通过三个实验系统地考查了人类短时距估计的标量特性、变异源、时距估计中的转换点和韦伯函数的形态等问题。结果表明,刺激物的运动、变化、速度和物理时距是被试进行短时距估计的重要变异源;被试在实验中表现出高估较短时距和低估较长时距的倾向,时距估计的转换点为11.1s;计时过程中得到的韦伯函数是个分段连续函数, 韦伯函数的拐点有两个12s和21s,这两点与本研究得到的时距估计转换点具有部分一致性     

Children Apply Principles of Physical Ownership to Ideas

Adults apply ownership not only to objects but also to ideas. But do people come to apply principles of ownership to ideas because of being taught about intellectual property and copyrights? Here, we investigate whether children apply rules from physical property ownership to ideas. Studies 1a and 1b show that children (6–8 years old) determine ownership of both objects and ideas based on who first establishes possession of the object or idea. Study 2 shows that children use another principle of object ownership, control of permission—an ability to restrict others’ access to the entity in question—to determine idea ownership. In Study 3 , we replicate these findings with different idea types. In Study 4 , we determine that children will not apply ownership to every entity, demonstrating that they do not apply ownership to a common word. Taken together, these results suggest that, like adults, children as young as 6 years old apply rules from ownership not only to objects but to ideas as well.     

Exploring the nature of cognitive flexibility

Cognitive flexibility is an important characteristic that helps humans pursue complex tasks, such as multitasking and finding novel, adaptable solutions to changing demands. Yet it is still a poorly understood construct. After briefly reviewing several investigations of this construct in cognitive science, I propose a unified account that considers cognitive flexibility a property of the cognitive system, rather than a cognitive skill. The emergence of cognitive flexibility is dependent on two kinds of interactions: the interaction of several cognitive mechanisms, and the interaction of sensorimotor mechanisms, cognition, and context in developmental time. The quest for a comprehensive and unified account of cognitive flexibility is highly justified given its potential usefulness in fostering efficient problem solving and creativity.     

Products of modal logics and tensor products of modal algebras

One of natural combinations of Kripke complete modal logics is the product, an operation that has been extensively investigated over the last 15 years. In this paper we consider its analogue for arbitrary modal logics: to this end, we use product-like constructions on general frames and modal algebras. This operation was first introduced by Y. Hasimoto in 2000; however, his paper remained unnoticed until recently. In the present paper we quote some important Hasimoto's results, and reconstruct the product operation in an algebraic setting: the Boolean part of the resulting modal algebra is exactly the tensor product of original algebras (regarded as Boolean rings). Also, we propose a filtration technique for Kripke models based on tensor products and obtain some decidability results.     

TEM study of defects generated in 4H-SiC by microindentations on the prismatic plane

The deformation microstructure of single crystals of 4H-SiC resulting from microindentations on a prismatic surface was investigated by TEM. Indentations were performed at 400 and 675°C, i.e. below the brittle to ductile transition temperature of 4H-SiC (temperature close to 1100°C). TEM analysis reveals dissociated dislocations as well as extended stacking faults in the basal plane. In addition, perfect edge dislocations are observed on prismatic planes. From the observations, it is assumed that perfect dislocations are nucleated in the prismatic plane and cross-slip on the basal one where they dissociate.