ZanteMatt

Anyone know an easy way to explain this question to me?

use laws or proposition to show that (a and notb) or b = a or b

Yes im leaving coursework to the last minute

Will Smith

dyofcw

georginho_juventusygr

I don't have any knowledge here. But let's try if I had to face this.

<pre class="ip-ubbcode-code-pre"> (a and not b) or b = a or b&lt;=&gt; (a and a) or b = a or b&lt;=&gt; a or b = a or bQ.E.D.</pre>

punkskamonkey

Depends what the a and b are surely?

You have to show that b and not b are mutually exclusive I think

martinji

it's literally years since I did this stuff. So I can't remember, but is the "or" operation associative, ie

(a and not b) or b
= (a or b) and (not b or b)
= (a or b) and TRUE
= a or b

Abe Lenstra

Let us beat about the bush no longer: The answer, off course, is 42.

paulcl

martinji's answer is right, except that it's "or" being distributive over "and", rather than associative, that's the key.