TY - JOUR AU - Łyczak, Marcin AU - Pietruszczak, Andrzej PY - 2018/12/30 Y2 - 2024/03/29 TI - On the Definability of Leśniewski’s Copula ‘is’ in Some Ontology-Like Theories JF - Bulletin of the Section of Logic JA - B Sect Log VL - 47 IS - 4 SE - Research Article DO - 10.18778/0138-0680.47.4.02 UR - https://czasopisma.uni.lodz.pl/bulletin/article/view/4776 SP - 233–263 AB - <p>We formulate a certain subtheory of Ishimoto’s [1] quantifier-free fragment of Leśniewski’s ontology, and show that Ishimoto’s theory can be reconstructed in it. Using an epimorphism theorem we prove that our theory is complete with respect to a suitable set-theoretic interpretation. Furthermore, we introduce the name constant 1 (which corresponds to the universal name ‘object’) and we prove its adequacy with respect to the set-theoretic interpretation (again using an epimorphism theorem). Ishimoto’s theory enriched by the constant 1 is also reconstructed in our formalism with into which 1 has been introduced. Finally we examine for both our theories their quantifier extensions and their connections with Leśniewski’s classical quantified ontology.</p> ER -