822.sagews

The following are examples of proper Tautologies:

DISJUNCTION: FALSE or TRUE, TRUE or FALSE

IMPLICATION: TRUE  if then TRUE or FALSE if then FALSE

EQUIVALENCE: TRUE if and only if TRUE or FALSE if and only if FALSE

import sage.logic.propcalc as propcalc 
Disjunction = propcalc.formula("(~A | A)"); 
Disjunction.truthtable();

A value False True True True

import sage.logic.propcalc as propcalc 
Implication = propcalc.formula("(~A -> ~A)"); 
Implication.truthtable();

A value False True True True

import sage.logic.propcalc as propcalc 
Equivalence = propcalc.formula("(~A <-> ~A)"); 
Equivalence.truthtable();

A value False True True True