effective procedure

In logic, an effective procedure is a procedure for solving problem by any intuitively ‘effective’ means from a specific class.

formation rules for propositional calculus

(wff: well-formed formula)

\begin{aligned} \text{FR1} &. \text{ A variable standing alone is a wff} \\ \text{FR2} &. \text{ If } \alpha \text{ is a wff, so is } \neg \alpha \\ \text{FR3} &. \text{ If } \alpha \text{ and } \beta \text{ are wffs, then } (\alpha \cdot \beta ), (\alpha \space \beta), (\alpha \vee \beta ), (\alpha \supset \beta), \text{ and } (\alpha \equiv \beta) \text{ are wffs} \end{aligned}