Mereology

2001, Lech Polkowski, Spatial Reasoning via Rough Sets, Wojciech Ziarko, Yiyu Yao (editors), Rough Sets and Current Trends in Computing: 2nd International Conference RSCTC 2000, Revised Papers, Springer, LNAI 2005, page 479, In [13] a new paradigm for approximate reasoning, rough mereology, has been introduced. Rough mereology is based on the notion of a part to a degree and thus falls in the province of part–based mereologies.

2007, Achille C. Varzi, Antony Galton (second reader), Chapter 15: Spatial Reasoning and Ontology: Parts, Wholes, and Locations, Marco Aiello, Ian Pratt-Hartmann, Johan van Benthem (editors), Handbook of Spatial Logics, Springer, page 947, Let us begin with mereology. This is often defined as the theory of the part-whole relation, but such a definition is misleading. It suggests that mereology has something to say about both parts and wholes, which is not true. As we shall see in Sec. 2, the notion of a whole goes beyond the conceptual resources of mereology and calls for topological concepts and principles of various sorts. By itself, mereology is best understood as the theory of the parthood relation, regardless of whether the second term of the relation may be said to qualify as a whole entity.

In 1926 Tarski drew Leśniewski's attention to the similarity existing between his mereology and Whitehead's theory of events.[…]In the United States, mereology is known as the “calculus of individuals” — a designation that is etymologically somewhat paradoxical, since the objects of mereology are anything but indivisible individua.