Learning about mathematical logic, I have to write formal deductions*.
How can I write them using TeX?
Any feedback is welcome.
(*)Roughly they are numbered lists over two columns, the first one gives a formula and the second one gives its justification (if it is an axiom, a hypothesis or if it is inferred by previous entries), both can go over many rows.
Anyway here is an example (from: Mendelson, Intro. to Math. Logic.)