Single Idea 13801

[catalogued under 5. Theory of Logic / H. Proof Systems / 1. Proof Systems]

Full Idea

An 'informal proof' is not in any particular proof system. One may use any rule of proof that is 'sufficiently obvious', and there is quite a lot of ordinary English in the proof, explaining what is going on at each step.

Gist of Idea

An 'informal proof' is in no particular system, and uses obvious steps and some ordinary English

Source

David Bostock (Intermediate Logic [1997], 8.1)

Book Reference

Bostock,David: 'Intermediate Logic' [OUP 1997], p.327