Why is 2nd First Order Logic Statement of "Infinitely Many Primes" Wrong? | Help

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SUMMARY

The discussion centers on the evaluation of two first-order logic statements regarding the assertion that there are infinitely many prime numbers. The second statement is deemed incorrect because it incorrectly implies that every integer p is prime, which is a misrepresentation of the concept. Both statements are equivalent in their logical structure, but the second's superfluous outer parentheses lead to confusion. A proper formalization requires a foundational understanding of set theory to define "finite set."

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  • Understanding of first-order logic statements
  • Familiarity with quantifiers in logic
  • Basic knowledge of prime numbers and their properties
  • Introduction to set theory concepts
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  • Study the principles of first-order logic and quantifier scope
  • Learn about the properties of prime numbers and their implications in number theory
  • Explore set theory fundamentals, particularly the definition of finite and infinite sets
  • Examine formal proofs regarding the infinitude of primes, such as Euclid's proof
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Students of mathematics, particularly those studying logic and number theory, as well as educators seeking to clarify misconceptions about prime numbers and logical statements.

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Homework Statement



The following are two first order logic statements of the statement "There are infinitely many prime numbers"

1. [PLAIN]http://uploadpie.com/3PZlO
2. [PLAIN]http://uploadpie.com/PN5i8

Can anyone explain why the second one is wrong? Thanks for help!

Homework Equations


The Attempt at a Solution

 
Last edited by a moderator:
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They are equivalent, so both are wrong.

They are equivalent because the scope of a quantifier, when not otherwise specified, is taken to be the entire statement to its right; so the outer pair of parentheses in the second statement is superfluous.

They are wrong because they assert, in part, that every integer p is prime.
 
[PLAIN]http://uploadpie.com/mHyHp

Is this correct?
 
Last edited by a moderator:
Yes, this is a correct statement that given any prime there is a greater prime. (Which implies there are infinitely many primes, but to state directly that there are infinitely many primes you need to formalize enough set theory to have a concept of "finite set".)
 

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