Constructing robust crew schedules with bicriteria optimization

Optimization‐based computer systems are used by many airlines to solve crew planning problems by constructing minimal cost tours of duty. However, today airlines do not only require cost effective solutions, but are also very interested in robust solutions. A more robust solution is understood to be one where disruptions in the schedule (due to delays) are less likely to be propagated into the future, causing delays of subsequent flights. Current scheduling systems based solely on cost do not automatically provide robust solutions. These considerations lead to a multiobjective framework, as the maximization of robustness will be in conflict with the minimization of cost. For example crew changing aircraft within a duty period is discouraged if inadequate ground time is provided. We develop a bicriteria optimization framework to generate Pareto optimal schedules for the domestic airline. A Pareto optimal schedule is one which does not allow an improvement in cost and robustness at the same time. We developed a method to solve the bicriteria problem, implemented it and tested it with actual airline data. Our results show that considerable gain in robustness can be achieved with a small increase in cost. The additional cost is mainly due to an increase in overnights, which allows for a reduction of the number of aircraft changes. Copyright © 2003 John Wiley & Sons, Ltd.     

心理定势现象的认知神经机制

问题解决活动中的心理定势,是指人们固执地沿用熟悉方案、忽略其他方案的反应倾向。它可能源于人们已经掌握的陈述性知识,也可能源于程序性知识,两类不同来源的心理定势的发生条件和影响效果都不尽相同。然而,过往的研究都没有做出严格区分。本文通过梳理相关研究,描述心理定势现象,解释心理定势是怎么发生的,分析心理定势是在什么条件下发生的、会对心理与行为活动造成什么样的影响,从而评述两种来源的心理定势的认知神经机制,指出尚未解决的科学问题。     

Constructing Cantorian counterexamples

Cantors diagonal argument provides an indirect proof that there is no one-one function from the power set of a set A into A. This paper provides a somewhat more constructive proof of Cantors theorem, showing how, given a function f from the power set of A into A, one can explicitly define a counterexample to the thesis that f is one-one.     

Disbelief,lies, and manipulations in a transactional discourse model

Disbelief, lies, and manipulations have been objects of scholarly consideration from widely different perspectives: historical, sociological, philosophical, ethical, logical, and pragmatic. In this paper, these notions are re-examined in the framework of a Transactional Discourse Model which operates in terms of the location and relocation of various knowledge items within two sets of knowledge, A and B, representing two interlocators A and B, and two of their subsets C_a and C_b, which constitute the sets of the matters of A's and B's current concern. This approach reveals certain formal features shared by lies, disbelief, and manipulations that indicate that these three types of discourse behavior constitute a deviation from successful interpersonal communication as defined in the proposed model. The model, moreover, enables us to explicitly capture both the similarities and the differences of lies and manipulations with other pragmatic phenomena, such as jokes, impersonating, role-acting, memory failure, politeness expressions, and tact; the comparison suggests that certain modifications of Gricean conversational maxims may be in order.     

Answer Sets and Qualitative Optimization

One of the major reasons for the success of answer set programmingin recent years was the shift from a theorem proving to a constraintprogramming view: problems are represented such that stablemodels, respectively answer sets, rather than theorems correspondto solutions. This shift in perspective proved extremely fruitfulin many areas. We believe that going one step further from a"hard" to a "soft" constraint programming paradigm, or, in otherwords, to a paradigm of qualitative optimization, will proveequally fruitful. In this paper we try to support this claimby showing that several generic problems in logic based problemsolving can be understood as qualitative optimization problems,and that these problems have simple and elegant formulationsgiven adequate optimization constructs in the knowledge representationlanguage.     

The Logic and Meaning of Plurals. Part II

In this sequel to “The logic and meaning of plurals. Part I”, I continue to present an account of logic and language that acknowledges limitations of singular constructions of natural languages and recognizes plural constructions as their peers. To this end, I present a non-reductive account of plural constructions that results from the conception of plurals as devices for talking about the many. In this paper, I give an informal semantics of plurals, formulate a formal characterization of truth for the regimented languages that results from augmenting elementary languages with refinements of basic plural constructions of natural languages, and account for the logic of plural constructions by characterizing the logic of those regimented languages.

Induction of Relational Schemas: Common Processes in Reasoning and Complex Learning

Five experiments were performed to test whether participants induced a coherent representation of the structure of a task, called a relational schema, from specific instances. Properties of a relational schema include: An explicit symbol for a relation, a binding that preserves the truth of a relation, potential for higher-order relations, omnidirectional access, potential for transfer between isomorphs, and ability to predict unseen items in isomorphic problems. However relational schemas are not necessarily coded in abstract form. Predictions from relational schema theory were contrasted with predictions from configural learning and other nonstructural theories in five experiments in which participants were taught a structure comprised of a set of initial-state,operator → end-state instances. The initial-state,operator pairs were presented and participants had to predict the correct end-state. Induction of a relational schema was achieved efficiently by adult participants as indicated by ability to predict items of a new isomorphic problem. The relational schemas induced showed the omnidirectional access property, there was efficient transfer to isomorphs, and structural coherence had a powerful effect on learning. The “learning to learn” effect traditionally associated with the learning set literature was observed, and the long-standing enigma of learning set acquisition is explained by a model composed of relational schema induction and structure mapping. Performance was better after reversal of operators than after shift to an alternate structure, even though the latter entailed more overlap with previously learned tasks in terms of the number of configural associations that were preserved. An explanation for the reversal shift phenomenon in terms of induction and mapping of a relational schema is proposed. The five experiments provided evidence supporting predictions from relational schema theory, and no evidence was found for configural or nonstructural learning theories.     

A linear conservative extension of Zermelo-Fraenkel set theory

In this paper, we develop the system LZF of set theory with the unrestricted comprehension in full linear logic and show that LZF is a conservative extension of ZF^– i.e., the Zermelo-Fraenkel set theory without the axiom of regularity. We formulate LZF as a sequent calculus with abstraction terms and prove the partial cut-elimination theorem for it. The cut-elimination result ensures the subterm property for those formulas which contain only terms corresponding to sets in ZF^–. This implies that LZF is a conservative extension of ZF^– and therefore the former is consistent relative to the latter. Hiroakira Ono     

Poor cognitive flexibility,and the experience thereof,in a subclinical sample of female students with obsessive‐compulsive symptoms

Research indicates that people with obsessive‐compulsive disorder (OCD) have poor cognitive flexibility. However, studies have largely focused on actual abilities and while individuals' emotional responses may be just as important, little is known about how those with OCD experience a situation that requires cognitive flexibility. It is furthermore largely unknown whether cognitive flexibility may also be important for people with OCD symptoms, rather than only to those with full blown disorders. This study investigates the relationship between cognitive flexibility, and the experience thereof in female students with and without OCD symptoms. It was expected that poor cognitive flexibility would be positively associated to OCD symptoms, and that those with OCD symptoms would display poor cognitive flexibility, and experience situations requiring cognitive flexibility as more difficult, than those without OCD symptoms. Participants completed a measure for OCD symptoms, a neuropsychological task to measure cognitive flexibility, and a self‐report measure assessing emotional experience of situations requiring cognitive flexibility. Positive associations between OCD symptoms and both poor cognitive flexibility and negative experience of situations requiring cognitive flexibility were found. Furthermore, those with OCD symptoms performed poorer on the cognitive flexibility task than those without OCD symptoms, and reported higher scores on the cognitive inflexibility questionnaire. Results confirm a relation between OCD symptoms and poor cognitive flexibility in a subclinical sample and identify a relation between OCD symptoms and a negative experience of situations that require cognitive flexibility. Overall findings suggest that poor cognitive flexibility may be an important part of OCD symptomatology.