Conditional ConnectivesThe statement `if p then q' is called a conditional statement and is written logically as p ! q.(This asserts that the truth of p guarantees the truth of q.)p ! q can also be read as `p implies q', where p is sometimes called the antecedent and qtheconsequent.Examples:p: It is raining.q: I get wet.p ! q: If it is raining, then I get wet.s: It is Sunday.w: I have to work today.s ! w: If it is Sunday, then I have to work today.»s ! w: If it is not Sunday, then I have to work today.s !»w: If it is Sunday, I do not have to work today.(s ^ p) !»w: If it is Sunday and it's raining, then I don't have to work today.To examine the truth or falsity of p ! q, suppose p and q are the following propositionsp: I win the lottery,q: I will buy you a car.Then p ! q is the statement `If I win the lottery, then I will buy you a car'.
The sum of p and q means (p+q). The difference of p and q means (p-q).
1)p->q 2)not p or q 3)p 4)not p and p or q 5)contrudiction or q 6)q
p*q
if the statement is : if p then q converse: if q then p inverse: if not p then not q contrapositive: if not q then not
p --> q and q --> p are not equivalent p --> q and q --> (not)p are equivalent The truth table shows this. pq p --> q q -->(not)p f f t t f t t t t f f f t t t t
The statement "if not p, then not q" always has the same truth value as the conditional "if p, then q." They are logically equivalent.
The relational operators: ==, !=, =.p == q; // evaluates true if the value of p and q are equal, false otherwise.p != q; // evaluates true of the value of p and q are not equal, false otherwise.p < q; // evaluates true if the value of p is less than q, false otherwise.p q; // evaluates true if the value of p is greater than q, false otherwise.p >= q; // evaluates true of the value of p is greater than or equal to q, false otherwiseNote that all of these expressions can be expressed logically in terms of the less than operator alone:p == q is the same as NOT (p < q) AND NOT (q < p)p != q is the same as (p < q) OR (q < p)p < q is the same as p < q (obviously)p q is the same as (q < p)p >= q is the same as NOT (p < q)
Conditional ConnectivesThe statement `if p then q' is called a conditional statement and is written logically as p ! q.(This asserts that the truth of p guarantees the truth of q.)p ! q can also be read as `p implies q', where p is sometimes called the antecedent and qtheconsequent.Examples:p: It is raining.q: I get wet.p ! q: If it is raining, then I get wet.s: It is Sunday.w: I have to work today.s ! w: If it is Sunday, then I have to work today.»s ! w: If it is not Sunday, then I have to work today.s !»w: If it is Sunday, I do not have to work today.(s ^ p) !»w: If it is Sunday and it's raining, then I don't have to work today.To examine the truth or falsity of p ! q, suppose p and q are the following propositionsp: I win the lottery,q: I will buy you a car.Then p ! q is the statement `If I win the lottery, then I will buy you a car'.
Converse: If p r then p q and q rContrapositive: If not p r then not (p q and q r) = If not p r then not p q or not q r Inverse: If not p q and q r then not p r = If not p q or not q r then not p r
The sum of p and q means (p+q). The difference of p and q means (p-q).
Not sure I can do a table here but: P True, Q True then P -> Q True P True, Q False then P -> Q False P False, Q True then P -> Q True P False, Q False then P -> Q True It is the same as not(P) OR Q
q + p
If p = 50 of q then q is 2% of p.
"The present list of 19 rules of inference constitutes a COMPLETE system of truth-functional logic, in the sense that it permits the construction of a formal proof of validity for ANY valid truth-functional argument." (FN1)The first nine rules of the list are rules of inference that "correspond to elementary argument forms whose validity is easily established by truth tables." (Id, page 351). The remaining ten rules are the Rules of Replacement, "which permits us to infer from any statement the result of replacing any component of that statement by any other statement logically equivalent to the component replaced." (Id, page 359).Here are the 19 Rules of Inference:1. Modus Ponens (M.P.)p qpq 2.Modus Tollens (M.T.)p q~q~p 3.Hypothetical Syllogism (H.S.)p qq rp r 4.Disjunctive Syllogism (D.S.)p v q~ pq 5. Constructive Dilemma (C.D.)(p q) . (r s)p v rq v s 6. Absorption (Abs.)p qp (p. q)7. Simplification (Simp.)p . qp 8. Conjunction (Conj.)pqp . q 9. Addition (Add.)pp v qAny of the following logically equivalent expressions can replace each other wherever they occur:10.De Morgan's Theorem (De M.) ~(p . q) (~p v ~q)~(p v q) (~p . ~q) 11. Commutation (Com.)(p v q) (q v p)(p . q) (q . p) 12. Association (Assoc.)[p v (q v r)] [(p v q) v r][p . (q . r)] [(p . q) . r] 13.Distribution (Dist) [p . (q v r)] [(p . q) v (p . r)][p v (q . r)] [(p v q) . (p v r)] 14.Double Negation (D.N.)p ~ ~p 15. Transposition (Trans.)(p q) (~q ~p) 16. Material Implication (M. Imp.)(p q) (~p v q) 17. Material Equivalence (M. Equiv.)(p q) [(p q) . (q p)](p q) [(p . q) v (~p . ~q)] 18. Exportation (Exp.)[(p . q) r] [p (q r)] 19. Tautology (Taut.) p (p v p)p (p . p)FN1: Introduction to Logic, Irving M. Copi and Carl Cohen, Prentice Hall, Eleventh Edition, 2001, page 361. The book contains the following footnote after this paragraph: "A method of proving this kind of completeness for a set of rules of inference can be found in I. M. Copi, Symbolic Logic, 5th Edition. (New York: Macmillian, 1979), chap 8, See also John A. Winnie, "The Completeness of Copi's System of Natural Deduction," Notre Dame Journal of Formal Logic 11 (July 1970), 379-382."
If p then q is represented as p -> q Negation of "if p then q" is represented as ~(p -> q)
p-q