src/HOL/ex/Guess.thy
author wenzelm
Tue, 22 Oct 2019 20:55:13 +0200
changeset 70923 98d9b78b7f47
parent 61343 5b5656a63bd6
permissions -rw-r--r--
clarified axiom_table: uniform space (e.g. like consts), e.g. relevant for export of HOL-ex.Join_Theory;

(*
    Author:     Makarius
*)

section \<open>Proof by guessing\<close>

theory Guess
imports Main
begin

notepad
begin
  have 1: "\<exists>x. x = x" by simp

  from 1 guess ..
  from 1 guess x ..
  from 1 guess x :: 'a ..
  from 1 guess x :: nat ..

  have 2: "\<exists>x y. x = x \<and> y = y" by simp
  from 2 guess apply - apply (erule exE conjE)+ done
  from 2 guess x apply - apply (erule exE conjE)+ done
  from 2 guess x y apply - apply (erule exE conjE)+ done
  from 2 guess x :: 'a and y :: 'b apply - apply (erule exE conjE)+ done
  from 2 guess x y :: nat apply - apply (erule exE conjE)+ done
end

end