15-317 Constructive Logic
Lecture 9: Sequent Calculus
In this lecture we develop the sequent calculus as a formal
system for proof search in natural deduction. Our sequent
calculus is designed to exactly capture the notion of a
verfication introduced in Lecture 3.
It differs in that all rules are applied bottom-up, from the
conclusion to the premise, unlike the introduction and elimination
rules that work bottom-up and top-down, respectively.
- Reading: 09-sequent.pdf
- Key concepts:
- Right rule
- Left rule
- Weakening and contraction
- Identity theorem
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