Chances are slight that Greg is a frog. It is certain that Bernhard is a rhino. It is probably the case that Jason is tired. Chances are slight that if either 'Jason is tired' or 'Greg is a frog' but not both then Julius is gray. There is little chance that if 'Greg is a frog and Jason is tired' then John went to the office. Chances are about even that if either 'Bernhard is a rhino' or 'Greg is a frog' but not both then Sandra dropped the milk.
It is probably not the case that 'Sandra dropped the milk and Jason is tired'.
It is probably not the case that 'Sandra dropped the milk and Jason is tired'.
It is highly likely that 'Sandra dropped the milk and Jason is tired'.

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

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

  query(conclusion).
  
'Sandra dropped the milk and Jason is tired'.