I'm having some difficulty with a problem I think.
If X = true and Y = true
((X AND Y)' AND (X' OR Y') ' ) '
I get back true. When I put it in Wolfram Alpha it gave me back false. But I think it may have had a ' by it as well? So I'm not really sure. I'm new to this and hoping for some clarification. My thinking was that:
((TRUE AND TRUE) ' AND (TRUE' OR TRUE') ' ) '
((FALSE AND FALSE) AND (FALSE OR FALSE) ' ) '
((FALSE) AND (FALSE) ' ) '
((FALSE) AND (TRUE)) '
((FALSE)) '
((TRUE))
Can someone please tell me if this is correct?
The ultimate result TRUE is correct, your calculation is wrong though.
If '
is the boolean negation which turns true to false and vice versa, you have made a mistake: you did not apply De Morgan's laws.
(A AND B)' = A' OR B'
(A OR B)' = A' AND B'
In particular
((FALSE) AND (TRUE))' = FALSE' OR TRUE'
which is still TRUE
.
Complete simplification of the expression is possible without making use of that law though, just by knowing how AND and OR are defined for two given booleans:
((TRUE AND TRUE)' AND (TRUE' OR TRUE')')' =
(TRUE' AND (FALSE OR FALSE)')' =
(FALSE AND FALSE')' =
(FALSE AND TRUE)' =
FALSE' =
TRUE
We can generalize even further: for any X and Y it is (now using the aforementioned law):
((X AND Y)' AND (X' OR Y')')' =
((X AND Y)' AND (X AND Y))' =
(Z' AND Z)' =
FALSE' =
TRUE
(with Z = X AND Y
)
So independent of how you choose X and Y, the result is TRUE.