Exercise 6.2 - Transition Execution

Logic Programming

What
versus
How

What is the result of applying the transition rule p(X,Y) ==> ~p(X,Y) & p(Y,X) to the dataset shown below?

correct(p(a,a))
correct(p(a,b))
correct(p(b,a))

official(S) :- setofall(P,correct(P),PS) & stringifyall(PS,S)
okay(S) :- readstringall(S,PS) & ~error(PS)

error(PS) :- correct(P) & ~member(P,PS)
error(PS) :- member(P,PS) & ~correct(P)

member(X,cons(X,L)) :- true
member(X,cons(Y,L)) :- member(X,L)

green("<img src='../images/greencheck.jpg'/>")
red("<img src='../images/redex.jpg'/>")

select(answer,S) & value(answer,OS) ==> ~value(answer,OS)
select(answer,S) ==> value(answer,S)

click(answer) & innerhtml(grade,OS) ==> ~innerhtml(grade,OS)
click(answer) ==> innerhtml(grade,"")

click(checkanswer) & value(answer,S) & okay(S) & green(G) ==> innerhtml(grade,G)
click(checkanswer) & value(answer,S) & ~okay(S) & red(G) ==> innerhtml(grade,G)

click(showanswer) & value(answer,OS) ==> ~value(answer,OS)
click(showanswer) & official(S) ==> value(answer,S)
click(showanswer) & innerhtml(grade,S) ==> ~innerhtml(grade,S)
click(showanswer) & green(S) ==> innerhtml(grade,S)

click(resetanswer) & value(answer,OS) ==> ~value(answer,OS)
click(resetanswer) & innerhtml(grade,S) ==> ~innerhtml(grade,S)
click(resetanswer) ==> innerhtml(grade,"")