This paper sets out to characterise and analyse logical atomism of Bertrand Russell. Main tenets of that theory are described by reference to Russell’s lecture Facts and Propositions (1918) and to other publications by that author. The essential claims of Russell’s position are discussed and confronted with tenets of ontology of situations developed by Bogusław Wolniewicz, a position inspired by logical atomism of Ludwig Wittgenstein. The author argues that several of Russell’s theses on logical atomism can be interpreted in the light of Wolniewicz’s ontology of situations. Finally, some minor concluding remarks are offered that can help to develop an ontology conceived in the spirit of the ontology of logical atomism. 366 Janusz Kaczmarek

Selected scientific contacts of Jacek Hawranek and Jan Zygmunt with Professor Bogusław Wolniewicz in the period from the end of the 1980s to the beginning of the 21st century are presented in this essay. They concerned the algebraic aspects of the ontology of situations and from one moment – one only question that was posed by Wolniewicz in his note A question about join-semilattices (Bulletin of the Section of Logic, 19/3, 1990, pp. 108–108), and resulted in the Hawranek & Zygmunt paper Wokół pewnego zagadnienia z dziedziny półkrat górnych z jednością (“Some comments on a question about semilattices with unit”) (Acta Universitatis Wratislaviensis 1445, Logika 15 (1993), pp. 59–68) containing an answer to Wolniewicz’s question. The Hawranek & Zygmunt paper is reprinted below, and the essay might be also treated as a kind of an analytical and historical introduction to it. The story of contacts Wolniewicz – Hawranek & Zygmunt has been told with the help of the preserved correspondence between the three persons. In his letters Professor Wolniewicz appears as a passionate researcher, open to discussion, ready to share his research successes and difficulties with others.

In this article I present the problem of identity of objects (that persist in time and space) and their identification (also in time and space, when these objects persist and change their location) indicated in the title of the paper. I therefore present an outline of P.F. Strawson’s proposal, but also a purely formal approach that can be found in formal sciences (logic and mathematics). In the final part I give some ontological solution to Strawson’s research. It is a solution based on formal considerations within the so-called ontologically oriented versions of modal and temporal logics, which I proposed in my book Indywidua. Idee. Pojęcia (2008).

Bogusław Wolniewicz, inspired by his formal ontology of situations, has put forward a question on semilattices with a unit (A question about joinsemilattices, Bulletin of the Section of Logic 19/3, 1990). The present paper is entirely devoted to this problem in the formulation given by Wolniewicz. First, the meaning of the question is analyzed and its lattice-theoretical and Boolean algebraic contents are exhibited. Second, set-theoretical and topological counterparts of the question are formulated and commented upon.