EntityQ3005945· pop 5· linked from 311 articlesformation ruleSign in to saverule for describing which strings of symbols formed from the alphabet of a formal language are syntactically valid within the languageConnectionsfirst-order logicEntityformal systemEntitysemantic theory of truthEntitymathematical logicEntitysemanticsEntityformal languageEntityquantifierEntityalphabetEntityrule of inferenceEntityrecursive setEntitywell-formed formulaEntitysemantics of logicEntitystructureEntitydiagramEntityground expressionEntitylogicEntityset theoryEntityfunctionEntitysetEntityaxiomEntityCategoriesFormal languagesLogical truthPredicate logicPropositional calculusRulesSyntax (logic)