It is probably the case that John left the apple. There is little chance that Brian is a frog. It is probably not the case that Bernhard is a rhino. There is almost no chance that if 'John left the apple and Bernhard is a rhino' then Gertrude is a cat. It is impossible that if either 'Bernhard is a rhino' or 'John left the apple' but not both then Sumit is thirsty. It is improbable that if 'Bernhard is a rhino' or 'John left the apple' or both then Mary went to the office.
It is impossible that 'Brian is a frog and Mary went to the office'.
It is impossible that 'Brian is a frog and Mary went to the office'.
There is a better than even chance that 'Brian is a frog and Mary went to the office'.

  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
  0.7::factA.
  0.1::factB.
  0.25::factC.
  %hop1
  0.02::factX:-and(factA,factC).
  0.0::factY:-xor(factC,factA).
  0.1::factZ:-or(factC,factA).

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

  query(conclusion).
  
'Brian is a frog and Mary went to the office'.