Answer: 1
To find the number of min-terms of the given Boolean expression, let us first simplify the expression inside the complement.
Let the given expression be F=G′, where:
G=D′+AB′+A′C+AC′D+A′C′D
Step 1: Simplify G
We can group the terms containing C′D:
AC′D+A′C′D=(A+A′)C′D=C′D
Substitute this back into the expression for G:
G=D′+AB′+A′C+C′D
Using the distributive law on D′+C′D:
D′+C′D=(D′+C′)(D′+D)=D′+C′
Now, substitute this back into G:
G=D′+C′+AB′+A′C
Using the identity X+X′Y=X+Y on C′+A′C (with X=C′ and Y=A′):
C′+A′C=C′+A′
This simplifies G to:
G=D′+C′+A′+AB′
Similarly, using the identity X′+XY=X′+Y on A′+AB′ (with X=A and Y=B′):
A′+AB′=A′+B′
Thus, the fully simplified expression for G is:
G=A′+B′+C′+D′
Step 2: Find F=G′
Using De Morgan's Law:
F=(A′+B′+C′+D′)′=A⋅B⋅C⋅D
Conclusion
The minimized expression is F=ABCD, which represents exactly 1 min-term (m15).