Build a truth table to verify that the proposition (p ↔ q)∧(¬p∧q) is a contradiction. 2.2. Logically Equivalent. Definition 2.2.1. Propositions r and s are
Show that (P ∧ Q) ∨ R is logically equivalent to (P ∨ R) ∧ (Q ∨ R) in two ways. (a) By using a truth table;. (b) By giving an explanation in words. 2
Prove that: [(p → q) ∧ (q → r)] → [p → r] is a tautology. By using truth table. By using logic equivalence laws. We will show these examples in class. c
(P ∧ Q) ∧ R P ∧ (Q ∧ R) are logically equivalent. • Law of This is the logical foundation of the 'contrapositive proof'. Page 21. A statement and its ...
Similarly (q ∨ r) ∧ p ⇔ (q ∧ p) ∨ (r ∧ p). The Laws of Logic can be used in several other ways. One of them is to prove that a statement is a tautology
) Show that ¬p → (q → r) and q → (p ∨ r) are logically equivalent ? Solution: Page 24. Math 151 Discrete Mathematics ( Propositional Logic ). By
p) is a tautology. Write a sentence that explains your conclusion. 2. [4] Use known logical equivalences to show that (p _ q) ! r is logically equivalent to. (p
show that (p → q) ∧ (p → r) is logically equivalent to p → (q∧r). Explain in a sentence why your truth table shows that they are logically equivalent. p q.
(q*prs) and (q*s) = (qs*). Several important laws of logic follow at once for example Ladd-Franklin's principle of the antilogism : (pq*r) = (pr*q) = (rq*p).
Show that P∧P is logically equivalent to P. Problem 1.3. Are the statement forms (P∧Q)∧R and P∧(Q∧R) logically equivalent? Problem 1.4. Are the
Propositions r and s are logically equivalent if the statement r ? s is a Show that (p ? q) ? (q ? p) is logically equivalent to p ? q. Solution 1.
24 Show that (p ? q) ? (p ? r) and p ? (q ? r) are logically equivalent. By the definition of conditional statements on page 6 using the Com- mutativity
Prove that: [(p ? q) ? (q ? r)] ? [p ? r] is a tautology. By using truth table. By using logic equivalence laws. We will show these examples in class. c
(¬p ? ¬p) ? (q ? r) Associative and Commutative Laws. ? ¬p ? (q ? r). Idempotent law. ? p ? (q ? r). Logical equivalence using conditionals.
) Show that ?p ? (q ? r) and q ? (p ? r) are logically equivalent ? Solution: Page 24. Math 151 Discrete Mathematics ( Propositional Logic ). By
Oct 3 2014 Write the following propositions using p
Jan 29 2015 Problem 3.1. Prove that (p ? q) ? (p ? r) and p ? (q ? r) are logically equivalent (without using this equivalence from the tables).
Show that ¬(p ? ¬q) and q ? ¬p are logically equivalent by (c) Prove or disprove that (p ? q) ? r and p ? (q ? r) are equivalent.
LOGIC. The conjunction of p and q (read: p and q) is the statement p ? q obtain the truth values of ¬p (¬p ? r)
Show that ¬(¬p) and p are logically equivalent. Since (p ? q) ?? ¬p ? ¬q is T in all cases therefore. (p ? q) ? ¬p ... The dual is p ? ¬q ? ¬r.
set of notes we have that pqis logically equivalent to (p)q) ^(q)p) Hence we can approach a proof of this type of proposition e ectively as two proofs: prove that p)qis true AND prove that q)pis true Indeed it is common in proofs of biconditional statements to mark the two proofs using
Two compound propositions p and q are logically equivalent if p ? q is a tautology ! Notation: p ? q ! De Morgan’s Laws: • ¬ (p ? q) ? ¬ p ? ¬ q • ¬ (p ? q) ? ¬ p ? ¬ q ! How so? Let’s build a truth table!
Constructing New Logical Equivalences We can construct new logical equivalences by applying known logically equivalent statements to show that A B Recall that two propositions p and q are logically equivalent if and only if p $q is a tautology (a k a their truth tables match)
The proposition p ? q read “p if and only if q” is called bicon-ditional It is true precisely when p and q have the same truth value i e they are both true or both false 1 1 4 Logical Equivalence Note that the compound proposi-tions p ? q and ¬p?q have the same truth values: p q ¬p ¬p?q p ? q T T F T T T F F F F F T T
A second notation often used to mean statements rand sare logically equivalent is r s You can determine whether compound propositions rand sare logically equivalent by building a single truth table for both propositions and checking to see that they have exactly the same truth values
P ?¬Q [P] [R] R ?¬P ¬P ¬R [Q] [¬Q] ¬R ¬R Q ?¬R I need to show Q ? ¬R I hope to getthisbyanapplicationof?Intro So I should try to prove ¬R under theassumptionQ FirstIlookatthe case P Ihopetoget¬R by¬Intro; so I assume R
Solution. 3. Use a truth table to show that ( p ? q) ? ( p ? r) and p ? ( q ? r) are logically equivalent. Solution. 4. Simplify the following statements (so that negation only appears right before variables).
Since p ? q is true if and p and q have the same truth values, in this course we will often build a truth table for the two statements and then remark on whether their columns are the same or different. Example 2.1.3. Prove the following are equivalent using a truth table. We use p ? q ? ¬ p ? q often enough that this has a name.
The logical equivalence of statement forms P and Q is denoted by writing P Q. Two statements are called logically equivalent if, and only if, they have logically equivalent forms when identical component statement variables are used to replace identical component statements. 2.1 Logical Equivalence and Truth Tables 4 / 9 Logical Equivalence
Show that (p?q) ? (p?r) and p? (q?r) are logically equivalent without using truth tables, but using laws instead. (Hint: s and t are logically equivalent, if s?t is a tautology.