Here is the solution given in my book to this problem
Could you please help to understand that marked area ? Is the book solution correct ?
I could not understand that marked part . I'm stuck at that part. Need help
Anyway, irrespective to the order that appears, you should realize that any variable multiplied to its inverse yields False (BB=0) as albbg said above, didn't you read?
Regardless of the utility of repeating the same term in this specific case, there is nothing to prevent you from doing so if you want to regroup miniterms into more simplified expressions; I assume you know that the sum of the same value in Boolean algebra is equal to itself.
Keep in mind that in K-map, it is usual to graphically enclose the same miniterms in different groups, and this is likely what may have been done in the book, better saying, could have been done just the same splitting procedure, but now performed in an algebraic fashion.
It was done so it's more obvious what the next operation is:
Code:
XY + X'Y' + X'YZ
XY + X'Y' + (X'Y' + X'YZ) - extra parenthesis are mine
XY + X'Y' + X'(Y' +YZ) - this can be reduced like the previous question you had on A + A'B
BTW that A + A'B is a variation on the Absorptive Law, A + AB = A