There is little chance that Bernhard is gray. Chances are slight that Mary went to the office. Chances are about even that Brian is a rhino. It is probably the case that if 'Mary went to the office' or 'Brian is a rhino' or both then Sumit is thirsty. We believe that if 'Bernhard is gray' or 'Mary went to the office' or both then Julius is a frog. It is unlikely that if 'Brian is a rhino' or 'Bernhard is gray' or both then Sandra grabbed the milk.
It is highly unlikely that 'Mary went to the office and Sumit is thirsty'.
It is highly unlikely that 'Mary went to the office and Sumit is thirsty'.
It is probably the case that 'Mary went to the office and Sumit is thirsty'.

  and(A,B) :- A,B.
  or(A,B) :- A;B.
  nand(A,B) :- not(and(A,B)).
  nor(A,B) :- not(or(A,B)).
  xor(A,B) :- or(A,B), nand(A,B).

  %hop0
  0.1::factA.
  0.1::factB.
  0.5::factC.
  %hop1
  0.7::factX:-or(factB,factC).
  0.75::factY:-or(factA,factB).
  0.2::factZ:-or(factC,factA).

  %hop2
  conclusion:-and(factB,factX).

  query(conclusion).
  
'Mary went to the office and Sumit is thirsty'.