DISCRETE MATH: Determine if two statements are logically equivalent

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SUMMARY

The discussion centers on determining the logical equivalence of the statements \forall\,x\,(P(x)\,\longleftrightarrow\,Q(x)) and \forall\,x\,P(x)\,\longleftrightarrow\,\forall\,x\,Q(x). It is concluded that these two statements are not logically equivalent, as demonstrated by setting P and Q to TRUE and FALSE. When both are TRUE, the statements hold equivalently, but they diverge when both are FALSE. The justification emphasizes the importance of clear notation in logical expressions.

PREREQUISITES
  • Understanding of logical equivalence in propositional logic
  • Familiarity with universal quantifiers in predicate logic
  • Basic knowledge of logical statements and truth values
  • Ability to manipulate and interpret logical expressions
NEXT STEPS
  • Study the properties of universal quantifiers in predicate logic
  • Learn about logical equivalences and their proofs
  • Explore the implications of truth tables in logical statements
  • Investigate common logical fallacies and misinterpretations
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Students of discrete mathematics, logic enthusiasts, and anyone seeking to deepen their understanding of logical equivalence and quantifiers in mathematical reasoning.

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Homework Statement



Determine whether [tex]\forall\,x\,(P(x)\,\longleftrightarrow\,Q(x))[/tex] and [tex]\forall\,x\,P(x)\,\longleftrightarrow\,\forall\,x\,Q(x)[/tex] are logically equivalent. Justify your answer.

Homework Equations



[tex]P\,\longleftrightarrow\,Q[/tex] is only TRUE when both P and Q are TRUE or FALSE.

The Attempt at a Solution



No, I don't think the two statements are logically equivalent, but I have trouble trying to "justify" my answer.

Set P and Q as always TRUE.

Both statements are equivalent, but if you set P and Q to always FALSE, then the statements are no longer equivalent.

Does this seem logical:rolleyes:
 
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Not very. Why not just write things out properly? As in for all z in S then P(z)
is just the same as z in S implies P(z).
 

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