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Example

We define

mult: R != 0 x R != 0 -> R != 0
mult(x, y) := x*y

For all real numbers x != 0, y != 0, we have

mult(x, y)/y = x.

However, we do not know the value of

mult(0, y)
therefore we must not conclude mult(0, y)/y = 0.
Author: Wolfgang Schreiner
Last Modification: October 14, 1999

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