9511 | We write the conditional 'if P (antecedent) then Q (consequent)' as P→Q [Lemmon] |
9508 | The sign |- may be read as 'therefore' [Lemmon] |
9512 | We write the 'negation' of P (not-P) as ¬ [Lemmon] |
9509 | That proposition that both P and Q is their 'conjunction', written P∧Q [Lemmon] |
9510 | That proposition that either P or Q is their 'disjunction', written P∨Q [Lemmon] |
9513 | We write 'P if and only if Q' as P↔Q; it is also P iff Q, or (P→Q)∧(Q→P) [Lemmon] |
9514 | If A and B are 'interderivable' from one another we may write A -||- B [Lemmon] |
12005 | The symbol 'ι' forms definite descriptions; (ιx)F(x) says 'the x which is such that F(x)' [Forbes,G] |
7799 | Proposition logic has definitions for its three operators: or, and, and identical [Girle] |