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Old October 23rd, 2009, 03:23 AM
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Default Simplifying a term

Hello,

Can anyone help me simplifying this term?

a AND (a xor b)

I know that I can write it like this:

(a AND not b) OR (not a AND b)

But how to simplify further? Would be grateful for any help. Thanks!
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Old October 23rd, 2009, 07:21 AM
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Quote:
Originally Posted by shadow147 View Post
Hello,

Can anyone help me simplifying this term?

a AND (a xor b)

I know that I can write it like this:

(a AND not b) OR (not a AND b)

But how to simplify further? Would be grateful for any help. Thanks!

(a AND not b) OR (not a AND b)

This is just equivalent to (a xor b), not the initial formula.
But, it turns out that all you need is the left disjunct.
That's the (perfect) disjunctive normal form for the initial formula.
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Old October 23rd, 2009, 01:47 PM
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Hello, shadow147!

I'll let you supply some of the reasons . . .


Quote:
Simplify: .a AND (a XOR b)

. . \begin{array}{ccc}a \cap \bigg[(a \cap b') \cup (a' \cap b)\bigg] & & \text{Given} \\ \\ \bigg[ a\cap (a \cap b')\bigg] \cup \bigg[a \cap(a'\cap b)\bigg] && \text{Distributive} \\ \\ \bigg[(a\cap a) \cap b'\bigg] \cup \bigg[(a\cap a') \cap b\bigg] & & \text{Associative}\end{array}

. . . . . \begin{array}{c}(a\cap b') \cup (f \cap b)  \\ \\(a \cap b') \cup f \\ \\ a \cap b' \end{array}

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Old October 23rd, 2009, 03:10 PM
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Awesome, much appreciated, thank you!
Just one question:

a\cap a'

Thats = 0 isn't it? Why did you replace it with f? And at the end you got

a\cap b' \cup f

Why is it possible to ignore the f and say that

(a\cap b')

is the result?
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