The property of a logical theory that whenever a wff is valid then it must also be a theorem. Symbolically, letting T represent a theory within logic L, this can be represented as the property that whenever T vDash 𝜙 is true, then T⊢𝜙 must also be true, for any wff φ of logic L.
The state or condition of being complete.
The inability to decide on a course of action, especially if two or more possibilities exist.