context: It is probably the case that Jessica is a sheep. There is little chance that Sandra dropped the milk. There is a better than even chance that Mary left the football. There is a very good chance that if 'Mary left the football and Sandra dropped the milk' then Bernhard is green. There is little chance that if 'Mary left the football and Sandra dropped the milk' then Brian is yellow. It is unlikely that if 'Mary left the football' or 'Jessica is a sheep' or both then Lily is a lion.
hypothesis: There is a better than even chance that 'Mary left the football and Brian is yellow'.
valid_hypothesis: It is impossible that 'Mary left the football and Brian is yellow'.
invalid_hypothesis: There is a better than even chance that 'Mary left the football and Brian is yellow'.
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
    0.7::factA.
    0.1::factB.
    0.6::factC.
    %hop1
    0.8::factX:-and(factC,factB).
    0.1::factY:-and(factC,factB).
    0.2::factZ:-or(factC,factA).
  
    %hop2
    conclusion:-and(factC,factY).
  
    query(conclusion).
    
hypothesis_assertion: 'Mary left the football and Brian is yellow'.