Exercise 4.3 - Action Execution

Computational Law

Law
without
Lawyers

Given the definition fix(X) :: p(X,Y) & p(Y,Z) ==> p(X,Z), what is the result of executing the action fix(a) on the dataset shown below.

correct(p(a,b))
correct(p(b,c))
correct(p(c,d))
correct(p(d,e))
correct(p(a,c))

official(S) :- evaluate(stringifyall(setofall(P,correct(P))),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,"")