sentence symbol मीनिंग इन हिंदी

Prove that if \ alpha is a wff in sentential logic and no sentence symbol appears twice in \ alpha then \ alpha and \ lnot \ alpha are both satisfiable.
One has a set of sentence variables, and one may perform various operations on the sentence variables; usually disjunction, conjunction, negation, and free algebraic structure in these operations on the set of sentence symbols.
Beginning with the sentence symbol S, and applying the phrase structure rules successively, finally applying replacement rules to substitute actual words for the abstract symbols, it is possible to generate many proper sentences of English ( or whichever language the rules are specified for ).