v1.4.18 — Add Recall subsections across the whole book (23 entries)
Every section with a References block (23 in total) now opens with a Recall subsection: the formal, citation-backed definition(s) that section uses, given as a verbatim quote followed by a short plain-English gloss, so a reader skimming back to check a term gets the precise definition immediately rather than a re-explanation. Inline citation markers were removed from body prose and “Mathematical reading” boxes throughout those files, since the formal citation now lives in Recall; References sections were trimmed to concise pointers.
Two mischaracterizations were caught and fixed while pulling verbatim quotes from source for this pass:
11-path-algebras/02-paths.mdmislabeled the path definition as Assem–Simson–Skowroński’s “Definition 1.2” — that numbered definition is actually the path algebra, built from paths; the path definition itself is unnumbered text immediately before it.- The “natural numbers object” Recall bullet added for
01-basics/01-everything-has-a-type.mdinitially quoted a functor-specific corollary sentence as if it were the general NNO definition; replaced with Jacobs’s actual general definition (zero/ successor diagram, universal property, functional notation).
Also fixed two explicitness gaps: Mac Lane’s “initial in C” and Jacobs’s “T : B → B” quotes now state explicitly that C/B are categories, rather than leaving that implicit.