Sequent-systems and groupoid models. I

The purpose of this paper is to connect the proof theory and the model theory of a family of propositional logics weaker than Heyting's. This family includes systems analogous to the Lambek calculus of syntactic categories, systems of relevant logic, systems related toBCK algebras, and, finally, Johansson's and Heyting's logic. First, sequent-systems are given for these logics, and cut-elimination results are proved. In these sequent-systems the rules for the logical operations are never changed: all changes are made in the structural rules. Next, Hubert-style formulations are given for these logics, and algebraic completeness results are demonstrated with respect to residuated lattice-ordered groupoids. Finally, model structures related to relevant model structures (of Urquhart, Fine, Routley, Meyer, and Maksimova) are given for our logics. These model structures are based on groupoids parallel to the sequent-systems. This paper lays the ground for a kind of correspondence theory for axioms of logics with implication weaker than Heyting's, a correspondence theory analogous to the correspondence theory for modal axioms of normal modal logics.The first part of the paper, which follows, contains the first two sections, which deal with sequent-systems and Hubert-formulations. The second part, due to appear in the next issue of this journal, will contain the third section, which deals with groupoid models.     

The real and the ideal; gender differences in heterosexual behaviour among Norwegian adolescents

This article focuses on gender differences in early heterosexual behaviour among Norwegian adolescents. The material comprised a random sample of 3000 Norwegian adolescents aged 17–19 years. The response rate was 63%. Data were collected by means of anonymous self-administered questionnaires. Sixty-nine per cent of the girls and 59% of the boys had had sexual intercourse. The majority of the adolescents, and a larger percentage of girls than of boys, had their first intercourse within a relationship of mutual commitment. The boys' first coital partners were 0.2 years younger than the boys themselves and the girls' partners were 2.8 years older than were the girls. Boys had had more coital partners than girls but girls had had intercourse more often than boys. Coital frequency was affected more by how long the adolescents had known the partner than by gender as such. In conclusion, boys and girls aged between 17 and 19 years form part of couples at two different stages of development. For this reason, boys and girls accumulate different sexual experiences in the early stage of their sexual careers.     

Preserved spatial memory in old rats survives 10 months without training

Aged rats with extensive prior training on the radial maze retain the capacity for accurate spatial working memory (WM) for at least 3 months without practice. To investigate the temporal limits of this influence of prior experience we compared the reacquisition of spatial WM by a group of experienced 21.5-month-old rats to the original acquisition by naive 3-month-old rats. The aged rats had received 225 radial maze tests between 3 and 11 months of age. Despite 10 months without practice the old rats rapidly reacquired critical performance. Their reacquisition was markedly superior to original learning by the young rats, even when delays as long as 5 h were imposed between the rats' fourth and fifth choices during the daily tests in the eight-arm maze. Additional tests showed that neither young nor old rats employed a response strategy to maintain accurate spatial WM performance. Experience clearly confers long-lived protection against the otherwise deleterious effects of aging on spatial WM, but the mechanism by which this influence arises is unknown.     

Impression management in behavior toward handicapped patients]

A previous study (Tr?ster, 1989) showed that nonhandicapped persons preferred a physically handicapped interaction partner to a nonhandicapped partner in an attributionally unambiguous situation. In order to test whether this "sympathy effect of physical handicap" is based on tendencies of impression management, 48 female subjects had to choose to sit next to either a physically handicapped or nonhandicapped female interaction partner in order to view a film together. Attributional ambiguity was varied by either confounding the choice of an interaction partner with a second, socially acceptable alternative (attributionally ambiguous situation: a choice between two films) or not confounding it (attributionally unambiguous situation: no choice between films). Public responsibility was manipulated by informing the subjects about their freedom to choose where they wished to sit either in public (public responsibility) or in private (no public responsibility). The results supported the impression management hypothesis: The handicapped interaction partner (in a wheelchair) was only preferred when the subjects had to anticipate that observers would deduce a preference of the chosen partner from the subjects' choices because of the attributionally unambiguous situation and the public announcement of their freedom of choice. Results suggest that the nonhandicapped strive to exhibit positive and nondiscriminative behavior toward the handicapped in order to avoid creating a disadvantageous impression in an observer.     

Problem-solving in a cooperative task in peach-fronted conures (Eupsittula aurea)

Animal Cognition - Cooperation is a complex behaviour found in many kinds of organisms and occurs between individuals of the same and different species. Several studies have examined the...     

Notes on Contributors

Biography

Notes on Contributors     

Descartes's Regulae, mathematics, and modern psychology: "the Noblest example of all" in Light of Turing's (1936) On computable Numbers

There are surprisingly strong connections between the philosophy of mind and the philosophy of mathematics. One particular important example can be seen in the Regulae (1628) of Descartes. In "the noblest example of all," he used his new abstract understanding of numbers to demonstrate how the brain can be considered as a symbol machine and how the intellect's algebraic reasoning can be mirrored as operations on this machine. Even though his attempt failed, it is illuminating to explore it because Descartes launched 2 traditions--mechanistic philosophy of mind and abstract mathematics--that would diverge until A. Turing (1936) approached symbolic reasoning in a similar "symbol machine-existence proof" way. Descrates's and Turing's thought experiments, which mark the beginning of modern psychology and cognitive science, respectively, indicate how important the development of mathematics has been for the constitution of the science of mind.     

Lateralization of squamous cell carcinomas in the head-neck region

Earlier studies have shown the lateralization of several immune disorders, including herpes zoster infection and breast cancer. We investigated whether there is lateralization of squamous cell carcinomas in the head-neck region and a relation of handedness with this cancer. Analysis showed right-sided lateralization of head-heck cancers in right-handed patients and vice versa in left-handed ones and a higher rate of left-handedness in patients with squamous cell cancer. Associations among left-handedness, squamous cell carcinoma, and its lateralization may result from a genetic togetherness.