The next meeting of the Algebra and Logic Seminar will take place on April 3, 2026 (Friday) at 1:00 pm (UTC+3) in online format via Zoom. A talk on: On Pairs of Non-commuting Hermitian Operators on the Unitary Plane which are Permutable Measurements will be delivered by Valentin Iliev (IMI-BAS). Abstract. In this presentation we study observables with spectre {-1,1} on quantum systems with the unitary plane as a space of states. Examples of such quantum systems are spin-1/2 particles. We find necessary and sufficient conditions for two non-commuting observables to be permutable measurements, that is, the probability of obtaining a particular pair of results does not depend on the order of taking these measurements. Several examples are presented. Link to the zoom meeting: https://us02web.zoom.us/j/88300991142?pwd=wGYl7VaD9RZKEm99sKzHMzl3bYCv3J.1 [...]