Set Theory Logic: Finding True Statements in a Given Domain

Click For Summary
SUMMARY

The discussion focuses on determining the truth values of the logical implication P(x) → Q(x) over the domain S = [-1, 1], where P(x) is defined as x ∈ [-1, 2] and Q(x) as x² ≤ 2. The truth table for the implication operator indicates that if P(x) is false, then P(x) → Q(x) is true regardless of Q(x). The participants explore whether there are values of x in S that make P(x) false, concluding that since all x in S satisfy P(x), the implication is not vacuously true.

PREREQUISITES
  • Understanding of logical implications in set theory
  • Familiarity with truth tables and their applications
  • Basic knowledge of inequalities and intervals
  • Concept of vacuous truth in logic
NEXT STEPS
  • Study the properties of logical implications in set theory
  • Learn about vacuous truth and its implications in mathematical logic
  • Explore the use of truth tables for complex logical expressions
  • Investigate the relationship between set intervals and inequalities
USEFUL FOR

Students of mathematics, particularly those studying logic, set theory, and mathematical proofs, as well as educators seeking to clarify concepts related to logical implications and truth values.

knowLittle
Messages
307
Reaction score
3

Homework Statement


In each of the two following open sentences P(x) and Q(x) over a domain S are given.
Determine all ##x \in S## for which P(x) → Q(x) is a true statement.

## P(x): x \in [-1, 2]; Q(x): x^{2} \leq 2; S=[-1,1] ##

Homework Equations


According to truth values for →:
a b a-> b
0 0 1
0 1 1
1 0 0
1 1 1

The Attempt at a Solution


If I can prove that P is False, then I will always get a T value for ->
Can I just say ## x \in [-1,1] ##, this would literally mean that statement P is false.
Could this count?
 
Physics news on Phys.org
Would this mean that the statement is true vacuously?
 
Is there any ##x \in S## such that P(x) is false?
 

Similar threads

Replies
8
Views
2K
Replies
1
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 14 ·
Replies
14
Views
4K
  • · Replies 18 ·
Replies
18
Views
2K
  • · Replies 11 ·
Replies
11
Views
3K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 23 ·
Replies
23
Views
2K
  • · Replies 15 ·
Replies
15
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K