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)

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