Nicod's axiom
Nicod's axiom is an axiom in propositional calculus that can be used as a sole wff in a two-axiom formalization of zeroth-order logic.
The axiom states the following always has a true truth value.
To utilize this axiom, Nicod made a rule of inference, called Nicod's modus ponens.
1. φ
2.
∴ ψ
In 1931, Mordechaj Wajsberg found an adequate, and easier-to-work-with alternative.
