Truth Values of Nested Qualifiers

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The discussion centers on the truth value of the nested quantifiers in the expression ∃x∃xP(x,y), where P(x,y) is defined as 2x + y = 1 and the domain for x and y is the set of all integers. Participants agree that the expression is flawed due to the lack of a distinct quantifier for y, suggesting it should be reformulated as ∃x∃yP(x,y) or possibly as ∀x∃yP(x,y) for clarity. The confusion arises from the incorrect repetition of the variable x, which leads to ambiguity in interpretation.

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nicnicman
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This problem doesn't make sense to me. Here it is:

Let P(x,y) denote the sentence 2x +y = 1
What is the truth value of ∃x∃xP(x,y) where the domain of x, y is the set of all integers.

Doesn't one of the variables need to be a y in ∃x∃xP(x,y)? In other words shouldn't the proposition be ∃x∃yP(x,y) or something similar?

Could this simply be a typo?

Thanks for any suggestions.
 
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nicnicman said:
This problem doesn't make sense to me. Here it is:

Let P(x,y) denote the sentence 2x +y = 1
What is the truth value of ∃x∃xP(x,y) where the domain of x, y is the set of all integers.

Doesn't one of the variables need to be a y in ∃x∃xP(x,y)? In other words shouldn't the proposition be ∃x∃yP(x,y) or something similar?

Could this simply be a typo?
Yes, there needs to be a quantifier for y.
My guess is that it ought to say [itex]\forall x\exists y:P(x,y)[/itex], or possibly with the quantifiers swapped (with a very different answer).
 

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