Here is a more important application  of CSP: Reasoning under Uncertainty.

You believe in the following English statements as follows:

friends of friends are friends   	0.7
friendless people smoke			2.3
smoking causes cancer			1.5
if two people are friends,
either both smoke or neither does	1.1
friends are symmetric (mutual)		10.0

Now consider Anna (A) and Bob (B).
We use the abbreviations:
Fr Friends
Sm Smokes
Ca Cancer

We get the following CSP problem: Domain = 0-1
Boolean variables 5: Fr(A,B), Sm(A), Sm(B), Ca(A), Ca(B)

Fr(A,B) or Sm(A)			2.3
Fr(B,A) or Sm(B)			2.3
!Sm(A) or Ca(A)				1.5
!Sm(B) or Ca(B)				1.5
!Fr(A,B) or Sm(A) or !Sm(B)		1.1
!Fr(A,B) or !Sm(A) or Sm(B)		1.1
!Fr(A,B) or !Fr(B,A) or Fr(A,A)		0.7
!Fr(B,A) or !Fr(A,B) or Fr(B,B)		0.7
!Fr(A,B) or Fr(B,A)			10.0
!Fr(B,A) or Fr(A,B)			10.0

Now assume we know that A and B are not friends:
!Fr(A,B)

What is the most likely state of the world? 
Solve the CSP problem: Both A and B smoke and both have cancer has the heighest weight: 
4.6 + 3 + 2.2 + 1.4 + 20 = 31.2