COP 5021 Lecture -*- Outline -*-

* Overview of Semantics (based on the book's section 2.2)

  The overall goal is to:
   - write a semantics for the programming language that is
     clearly correct, and
   - use it to prove that the analysis is correct

  As an example, this section uses structural operational semantics
  to show that the live variables analysis is correct.

  Q:  Why are formal correctness proofs useful for program analysis?
  a way to find subtle errors and correct them

** kinds of semantics
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      KINDS OF SEMANTICS

Axiomatic

  Semantics as declarative specifications
    - predicates + predicate transformers

Denotational

  Semantics as functional program
     domains + meaning functions

Operational

  Semantics as logic programming
     configurations + rewrite rules

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       These approaches can be prototyped:
         - axiomatic: in an automatic theorem prover,
           like Isabelle HOL or Coq
         - denotational: in a functional programming language,
           like Haskell
         - operational: in a logic programming language,
           like (lambda) Prolog