Diagrams
General-purpose packages for drawing diagrams
pgf and TikZ(Till Tantau 2005–16, now The PGF/TikZ Team): a general TeX macro package for generating graphics, with a user-friendly syntax layer called TikZ.
XY-pic (Kristoffer Rose and Ross Moore 1991–2013; extremely powerful and versatile: there’s a chapter on this in The LaTeX Graphics Companion)
Diagrams for modal logicians
A Quick TikZ Guide for Modal Logicians (Alex Kocurek, 2020)
Diagrams of sphere models for variably strict conditionals (Richard Zach 2018)
Commutative diagrams for category theory
There is a useful Guide to commutative diagrams packages (J.S. Milne). But the headline recommendations are
diagrams.tex (Paul Taylor 1986–2019), classic macros: much used and usually highly rated – though not so much by Milne – for drawing simple or very complicated commutative diagrams for category theory.
tikz-cd (Florencio Neves, Augusto Stoffel 2012–21). This package facilitates the creation of commutative diagrams in TikZ by providing a convenient set of macros and reasonable default settings. This is what I use: but (a TikZ issue, I believe) a diagram-heavy document can be slow to generate a PDF: you might want to investigate and use the “memoize” package so that (unchanged) diagrams are not re-processed every time you re-typeset your document, considerably speeding things up.
Other resources
Tree drawing in LaTeX (from LaTeX for Linguists)
The semantics package supplies T-diagrams and other resources.
Dednat (Eduardo Ochs, 2019) processes proofs or diagrams written without markup, using LuaLaTeX.
The logix package (Michael Finney 2001-2022) provides knot symbols for constructing knot diagrams.
Checked 9 October 2024