context: It is highly likely that Mary went to the bedroom. It is highly likely that John took the football. It is likely that Bernhard is a lion. It is certain that if either 'John took the football' or 'Mary went to the bedroom' but not both then Brian is a rhino. It is probably not the case that if 'John took the football' or 'Bernhard is a lion' or both then Sandra dropped the apple. It is almost certain that if 'Bernhard is a lion and John took the football' then Jeff moved to the garden.
hypothesis: Chances are about even that 'Brian is a rhino' or 'Sandra dropped the apple' or both.
valid_hypothesis: Chances are about even that 'Brian is a rhino' or 'Sandra dropped the apple' or both.
invalid_hypothesis: It is certain that 'Brian is a rhino' or 'Sandra dropped the apple' or both.
problog: 
    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
    0.9::factA.
    0.9::factB.
    0.7::factC.
    %hop1
    1.0::factX:-xor(factB,factA).
    0.25::factY:-or(factB,factC).
    0.95::factZ:-and(factC,factB).
  
    %hop2
    conclusion:-or(factX,factY).
  
    query(conclusion).
    
hypothesis_assertion: 'Brian is a rhino' or 'Sandra dropped the apple' or both.