In a truth table, the expression true and true is false. A truth table is a mathematical table thar is used in logic. It is specifically connected with Boolean algebra, boolean functions, and propositional calculu. That arrange the functional values of logical expressions on each of their functional arguments. The meaning is that for each combination of values taken by their logical variables. Particularly, it can be used to demonstrate whether a propositional expression is true for all legitimate input values, that is, logically valid.