Preservation
In truth-preserving validity, the interpretation under which all variables are assigned a truth value of 'true' produces a truth value of 'true'.
In a false-preserving validity, the interpretation under which all variables are assigned a truth value of 'false' produces a truth value of 'false'.
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Preservation properties Logical connective sentences True and false preserving: Logical conjunction (AND, ) • Logical disjunction (OR, ) True preserving only: Tautology ( ) • Biconditional (XNOR, ) • Implication ( ) • Converse implication ( ) False preserving only: Contradiction ( ) • Exclusive disjunction (XOR, ) • Nonimplication ( ) • Converse nonimplication ( ) Non-preserving: Proposition • Negation ( ) • Alternative denial (NAND, ) • Joint denial (NOR, )
Read more about this topic: Validity
Famous quotes containing the word preservation:
“There is something to be said for jealousy, because it only designs the preservation of some good which we either have or think we have a right to. But envy is a raging madness that cannot bear the wealth or fortune of others.”
—François, Duc De La Rochefoucauld (1613–1680)
“I do seriously believe that if we can measure among the States the benefits resulting from the preservation of the Union, the rebellious States have the larger share. It destroyed an institution that was their destruction. It opened the way for a commercial life that, if they will only embrace it and face the light, means to them a development that shall rival the best attainments of the greatest of our States.”
—Benjamin Harrison (1833–1901)
“It is my hope to be able to prove that television is the greatest step forward we have yet made in the preservation of humanity. It will make of this Earth the paradise we have all envisioned, but have never seen.”
—Joseph O’Donnell. Clifford Sanforth. Professor James Houghland, Murder by Television, just before he demonstrates his new television device (1935)