How Do You Identify XOR in Karnaugh Maps?

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In summary, the computer science teacher taught students how to solve the homework equation using Reed Muller logic. First, they list all the 1s and then use XOR operations to get the answer.
  • #1
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Homework Statement



Using XK-map techniques, obtain the minimum Boolean expression for the following map:

Screen Shot 2015-04-19 at 1.58.29 PM.png


Homework Equations

The Attempt at a Solution



So I've been doing some reading and I found this has to do with Reed Muller logic. This was unfortunately not covered in the course I'm taking, so I'm a tad bit confused.

How exactly am I supposed to circle this map? I know I have to circle groups of zeroes and ones such that the parity of the ones is odd and the parity of the zeroes is even.

For reference, the answer is listed as:

$$Z = \bar a \bigoplus b \bigoplus c \bigoplus d$$

I have experimented with a few circling combinations, but cannot find one that gives the answer above.
 
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  • #2
You could "circle" the four "0" for not A i guess. They all have odd parity for B,C,D. Similar for A.
That does not give nice square blocks - it cannot, you are looking for XOR.
 
  • #3
After staring at this for a few more minutes, I came up with this:

Screen Shot 2015-04-19 at 1.58.29 PM.png


So the black box would be ##\bar a##. The red box would be ##b##. The blue box would be ##c##. The green box would be ##d##.

So ##z = \bar a \oplus b \oplus c \oplus d##.
 
Last edited:
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  • #4
I am in high school and my Computer Science teacher teach us this and I figure it out by kinda like a Math way.
First I list out all the 1s.
A'B'C'D'+A'B'CD+A'BC'D+A'BCD'+ABC'D'+ABCD+AB'C'D+AB'CD'
=(A'B'C'D'+A'BCD'+ABC'D'+AB'CD')+(A'B'CD+A'BC'D+ABCD+AB'C'D)
=D'(A'B'C'+A'BC+ABC'+AB'C)+D(A'B'C+A'BC'+ABC+AB'C')
=D'(C'[A'B'+AB]+C[A'B+AB'])+D(C[A'B'+AB]+C'[A'B+AB'])
RECALL THAT
A'B + AB' = A XOR B
A'B' + AB= A XNOR B

=D'(C'[A XNOR B]+C[A XOR B]) + D(C[A XNOR B]+C'[A XOR B])
WHILE XNOR = (XOR)'
=D'(C'[A XOR B]'+C[A XOR B]) + D(C[A XOR B]'+C'[A XOR B])
=D'([A XOR B] XNOR C)+ D([A XOR B] XOR C)
=D'(A XOR B XOR C)' + D(A XOR B XOR C)
=A XOR B XOR C XNOR D
=A ⊕ B ⊕ C ⊕ D'
OR IF U PULL OUT 'A' AT FIRST IT WILL BE THE SAME
 

Related to How Do You Identify XOR in Karnaugh Maps?

1. What is a K-Map and how is it used to identify XOR?

A K-Map, short for Karnaugh map, is a graphical method used to simplify boolean expressions. It is commonly used in digital circuit design. To identify XOR in a K-Map, we look for groups of cells that form a rectangle or square shape on the map.

2. Can XOR be identified in a K-Map with more than 4 variables?

Yes, XOR can be identified in a K-Map with any number of variables, but it becomes more complex and difficult to visualize as the number of variables increases. It is recommended to use a computer algorithm or truth table to identify XOR in K-Maps with more than 4 variables.

3. How do I know if a group of cells in a K-Map represents XOR?

If a group of cells in a K-Map contains an odd number of 1s, it represents XOR. This is because XOR is only true when the input values are different (one 1 and one 0).

4. Are there any special cases when identifying XOR in a K-Map?

Yes, there are two special cases to consider when identifying XOR in a K-Map. The first is when there is only one cell with a 1, in which case it does not represent XOR. The second is when there are no cells with a 1, in which case it represents a logical 0 (false) output.

5. Can a K-Map be used to identify XOR in both SOP and POS forms?

Yes, a K-Map can be used to identify XOR in both Sum of Products (SOP) and Product of Sums (POS) forms. In SOP form, we look for groups of cells with 1s, while in POS form, we look for groups of cells with 0s. The resulting expressions will be different, but they both represent XOR.

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