Comma titles that follow a name: "John Smith, Ph.D." Similarly in lists that are presented with an inversion: "...; socks, green: 3 pairs; socks, red: 2 pairs; tie, regimental: 1". Commas may be used to indicate that a word, or a group of words, has been omitted, as in "The cat was white; the dog, brown." (Here the comma replaces "was".) Commas are placed before, after, or around a noun or pronoun used independently in speaking to some person, place or thing: In his 1785 essay "An Essay on Punctuation", Joseph Robertson advocated a comma between the subject and predicate of
Comma category by Lawvere, which involved the comma punctuation mark. Although standard notation has changed, since the use of a comma as an operator is potentially confusing, and even Lawvere dislikes the uninformative term "comma category" (Lawvere, 1963 p. 13), the name persists. The most general comma category construction involves two functors with the same codomain. Often one of these will have domain 1 (the one-object one-morphism category). Some accounts of category theory consider only these special cases, but the term comma category is actually much more general. Suppose that formula_1, formula_2, and formula_3 are categories, and formula_4 and formula_5 (for source