The Smith family and their three children want to pay a visit but they do not all have the time to do so. Following are few hints who will go and who will not:

o If Mr Smith comes, his wife will come too. o At least one of their two sons Matt and John will come. o Either Mrs Smith or Tim will come, but not both. o Either Tim and John will come, or neither will come. o If Matt comes, then John and his father will also come.

The following query will solve the problem:

[user]  ?-  Mr_Smith_comes  =>  Mrs_Smith_comes,
|  Matt_comes  \/  John_comes  <=>  1,
|  Mrs_Smith_comes  #  Tim_comes  <=>  1,
|  Tim_comes  <=>  John_comes,
|  Matt_comes  =>  John_comes  /\  Mr_Smith_comes,
|  label(Mr_Smith_comes,  Mrs_Smith_comes,
|  Matt_comes,  John_comes,  Tim_comes]).


Mr_Smith_comes      =  0
Mrs_Smith_comes     =  0
Matt_comes          =  0
John_comes          =  1
Tim_comes           =  1

yes