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cases : string -> thm

SYNOPSIS

Produce cases theorem for an inductive type.

DESCRIPTION

A call cases "ty" where "ty" is the name of a recursive type defined with define_type, returns a ``cases'' theorem asserting that each element of the type is an instance of one of the type constructors. The effect is exactly the same is if prove_cases_thm were applied to the induction theorem produced by define_type, and the documentation for prove_cases_thm gives a lengthier discussion.

FAILURE CONDITIONS

Fails if ty is not the name of a recursive type.

EXAMPLE

  # cases "num";;
  val it : thm = |- !m. m = 0 \/ (?n. m = SUC n)

  # cases "list";;
  val it : thm = |- !x. x = [] \/ (?a0 a1. x = CONS a0 a1)