math 1: logic ch 19 Flashcards
a statement is a sentence for which it is meaningful to say
that it is true or false
negation of a statement is the statement formed by putting the words… in front of the original statement
“it is not true that”
the symbol… is used for negation
~
a statement and its negation have opposite
truth values
if p is true ~p is
false
if p is false ~p is
true
if a statement claims that all objects of a certain type have a particular property, the negation of that statement says that at least
one of those objects does not have the property
if a statement claims that some object of a certain type has a particular property, the negation of that statement says that
none of those objects has the same property
a conditional statement is a sentence of the form “if p, then q” where p and q are given statements this is written
p→q and is read “p implies q”
the converse of p→q is
q→p (order of statements reversed)
inverse of p→q is
~p→~q (original statements are negated)
contrapositive of p→q is
~q→~p (order of statements reversed and statements negated)
whether a conditional statement is true or false, its contrapositive always has the same
truth value
a conditional statement is logically equivalent to its ….Either both statements are … or both are ….
contrapositive; true; false
the converse and inverse of a conditional statement are ….. either both statements are … or both are…
logically equivalent; true; false