context: Chances are slight that Bernhard is white. Chances are about even that Mary moved to the office. There is a very good chance that John discarded the apple. It is highly unlikely that if 'Mary moved to the office and John discarded the apple' then Lily is a frog. It is likely that if 'Mary moved to the office' or 'Bernhard is white' or both then Jeff went to the garden. We doubt that if either 'Bernhard is white' or 'Mary moved to the office' but not both then Bill got the milk there.
hypothesis: Chances are slight that 'Bernhard is white and John discarded the apple'.
valid_hypothesis: Chances are slight that 'Bernhard is white and John discarded the apple'.
invalid_hypothesis: It is likely that 'Bernhard is white and John discarded the apple'.
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
    0.1::factA.
    0.5::factB.
    0.8::factC.
    %hop1
    0.05::factX:-and(factB,factC).
    0.7::factY:-or(factB,factA).
    0.2::factZ:-xor(factA,factB).
  
    %hop2
    conclusion:-and(factA,factC).
  
    query(conclusion).
    
hypothesis_assertion: 'Bernhard is white and John discarded the apple'.