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Proof by Case Distinction
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Typical Use
Example
We prove
forall
x in
R
:
x
*
x
!= -1. Take arbitrary
x
in
R
.
If
x
>= 0
, then
x
*
x
>= 0.
If
x
< 0
, then also
x
*
x
>= 0.
Author:
Wolfgang Schreiner
Last Modification: November 30, 1999