It is probable that Brian is a swan. We doubt that Bernhard is a swan. It is probably the case that John went to the office. Chances are about even that if 'Brian is a swan and John went to the office' then Jeff dropped the apple. There is little chance that if 'John went to the office and Brian is a swan' then Jason is bored. It is impossible that if either 'John went to the office' or 'Brian is a swan' but not both then Lily is a lion.
It is impossible that 'Jason is bored and Bernhard is a swan'.
It is impossible that 'Jason is bored and Bernhard is a swan'.
It is probably the case that 'Jason is bored and Bernhard is a swan'.

  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.
  0.2::factB.
  0.7::factC.
  %hop1
  0.5::factX:-and(factA,factC).
  0.1::factY:-and(factC,factA).
  0.0::factZ:-xor(factC,factA).

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

  query(conclusion).
  
'Jason is bored and Bernhard is a swan'.