On comparison of theories by their contents

Popper's definition of verisimilitude was criticized for its paradoxical consequences in the case of false theories. The aim of this paper is to show that paradoxes disappear if the falsity content of a theory is defined with help of dCn or Cn ^–1.To the memory of Jerzy SupeckiI am grateful to David Pearce, Gerhard Schurz, Peter Simons, Maciej Spasowski and Jan Zygmunt for their helpful discussions on issues analysed in this paper. Particularly, Zygmunt's and Spasowski's comments enabled me to correct several mistakes of the earlier drafts.     

No non-trivial quasivariety of BCK-algebras has decidable first order theory

Using the semantic embedding technique the theorem announced by the title is proved.     

Wprowadzanie implikacji na kursach logiki usługowej

Allatum est die 1 Augusti 1969     

Przegląd niektórych zagadnień logiki pytań

Allatum est die 9 Martii 1965     

Problematyka indukcji w pracach i działalności Kazimierza Ajdukiewicza

Allatum est die 10 Aprilis 1964     

On estimating inter-subject variability of choice probabilities under observability constraints

Methods are presented for estimating inter-subject variability of the probability of a given event defined in terms of subject's behavior (e.g., probability of a given choice in a discrimination experiment). The constraints consist of using no more than two independent observations for each subject. Estimators are provided for assessing the inter-subject “variance” of the analyzed probabilities; also, a method is given for testing the hypothesis that the average probability is the same for two groups of subjects.