src/HOL/ex/Guess.thy
 author bulwahn Fri Jan 07 14:46:28 2011 +0100 (2011-01-07) changeset 41460 ea56b98aee83 parent 20005 3fd6d57b16de child 58889 5b7a9633cfa8 permissions -rw-r--r--
removing obselete Id comments from HOL/ex theories
```     1 (*
```
```     2     Author:     Makarius
```
```     3 *)
```
```     4
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```     5 header {* Proof by guessing *}
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```     6
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```     7 theory Guess
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```     8 imports Main
```
```     9 begin
```
```    10
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```    11 lemma True
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```    12 proof
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```    13
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```    14   have 1: "\<exists>x. x = x" by simp
```
```    15
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```    16   from 1 guess ..
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```    17   from 1 guess x ..
```
```    18   from 1 guess x :: 'a ..
```
```    19   from 1 guess x :: nat ..
```
```    20
```
```    21   have 2: "\<exists>x y. x = x & y = y" by simp
```
```    22   from 2 guess apply - apply (erule exE conjE)+ done
```
```    23   from 2 guess x apply - apply (erule exE conjE)+ done
```
```    24   from 2 guess x y apply - apply (erule exE conjE)+ done
```
```    25   from 2 guess x :: 'a and y :: 'b apply - apply (erule exE conjE)+ done
```
```    26   from 2 guess x y :: nat apply - apply (erule exE conjE)+ done
```
```    27
```
```    28 qed
```
```    29
```
```    30 end
```