4: First-Order Logic
- Page ID
- 23905
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Three Logicians walk into a bar, and
the barkeeper asks “Would you all like something to drink?”
The 1st Logician says “I don’t know,”
and the 2nd Logician says “I don’t know.”
Then the 3rd Logician says “yes.”
author unknown
- 4.4: The Introduction and Elimination Rules for Quantifiers
- As you know, there are two quantifiers ( ∃ and ∀ ). Each of these has an introduction rule and an elimination rule, so there are 4 rules to present in this section. Proofs in can use both of these rules, plus all of the rules of (such as the rules of negation and the basic theorems, including introduction and elimination rules), and also any other theorems that have been previously proved.