the question asks me to implement a certain function in a minimal way
using a MUX
i have constructed a Karno table
and found the minimal function which consists only from the variables a,c,d

now in the solution they constructed a table only from a,c,d varibles

http://s290.photobucket.com/albums/l...t=IMG_8818.jpg

i am having trouble to understand it because for every value of a,c,d
we have two cells in the original karno table
so how they deside which value belongs to each cell in the a,c,d table
???????