Skip to content
Free public beta until December 4, 2026: every course is open, no card needed. After that, the first chapter of each course stays free and full access is a one-time $39 ($19 for up to 100 founding members chosen for helpful feedback). Your progress is kept. How the beta works

logic

Recognizing substitution instances of a form

taught

Tell whether a given argument fits a given form, with the same claim in the same slot every time.

Taught in

Requires

Required by