Stockholm University

About: Stockholm University is a education organization based out in Stockholm, Sweden. It is known for research contribution in the topics: Population & Context (language use). The organization has 21052 authors who have published 62567 publications receiving 2725859 citations. The organization is also known as: University of Stockholm & Stockholms universitet.

Ideas and Results in Proof Theory

Abstract: Publisher Summary This chapter presents an exposition of certain themes in proof theory. The chapter discusses ideas behind what may be called Gentzen-type analysis in proof theory, where in particular, one wants to draw attention to the fact that they constitute the embryo to a general proof theory; extensions of the results obtained by Gentzen to more powerful theories; and the connection between proofs and the terms used in functional interpretations of intuitionistic logic, in particular, the connection between Gentzen-type analysis and the Godel-type analysis that originated with Godel's socalled Dialectica interpretation. A notion of validity of derivations is presented that may be contemplated as a possible explication of Gentzen's ideas about an operational interpretation of the logical constants. Proofs of the results have shown how this notion of validity may be used as a convenient tool to establish the main result about strong normalization in first order logic.

Why Copy Others? Insights from the Social Learning Strategies Tournament

Abstract: Social learning (learning through observation or interaction with other individuals) is widespread in nature and is central to the remarkable success of humanity, yet it remains unclear why copying is profitable and how to copy most effectively To address these questions, we organized a computer tournament in which entrants submitted strategies specifying how to use social learning and its asocial alternative (for example, trial-and-error learning) to acquire adaptive behavior in a complex environment Most current theory predicts the emergence of mixed strategies that rely on some combination of the two types of learning In the tournament, however, strategies that relied heavily on social learning were found to be remarkably successful, even when asocial information was no more costly than social information Social learning proved advantageous because individuals frequently demonstrated the highest-payoff behavior in their repertoire, inadvertently filtering information for copiers The winning strategy (discountmachine) relied nearly exclusively on social learning and weighted information according to the time since acquisition

Osseointegrated Oral Implants

Abstract: Fourteen Swedish teams outside the University of Gothenburg, each with minimally three years' experience in the Nobelpharma osseointegrated implant participated in a retrospective multiclinic study. The total number of consecutively inserted implants at the 14 clinics was 8139. The outcome of every implant was reported and all implant failures, irrespective of when they occurred, were published. The success criteria included absence of implant mobility, absence of radiolucent zones on x-rays, and an annual bone loss after the first year of less than 0.2 mm. In the mandible 334 implants were followed for five to eight years, with only three failures, for a success rate of 99.1%. In the maxilla 106 implants were followed for five to seven years, with a success rate of 84.9%. In irradiated and grafted mandibles, 56 implants were inserted and none was lost during a follow-up of up to five years. In the irradiated maxilla there were 16 implants inserted with three reported failures and in the grafted upper jaw 71 implants were inserted with 12 failures. The proportions of mandibular and maxillary sleeping implants were 0.8 and 0.3%, of patient drop-out implants 0.3 and 0.6%, and of patient death implants 0.9 and 1.2%, respectively. It was concluded that the osseointegrated implant, if inserted according to the guidelines of Branemark, results in a very high degree of clinical success, thereby meeting any published oral implant success criteria.