Given the following graph of possible flights between seven US cities: (graph ta

Question

Given the following graph of possible flights between seven US cities: (graph taken from the web site of the American Mathematical Society, http://www.ams.org) Define a predicate route/3 that takes two cities as arguments and finds the routes to get from city A to a city B. Your predicate should have the signature route(cityA, cityB, Route). Examples:

?- route(seattle, boston, X).

X = [seattle, omaha, atlanta, boston] ; false.

?- route(fresno, atlanta, X).

X = [fresno, seattle, omaha, atlanta] ;

X = [fresno, albany, seattle, omaha, atlanta] ;

X = [fresno, albany, dallas, seattle, omaha, atlanta] ;

false.

?- route(albany, atlanta, X).

X = [albany, seattle, omaha, atlanta] ;

X = [albany, dallas, seattle, omaha, atlanta] ;

false.

?- route(boston, atlanta, X).

Explanation / Answer

Please find my answer.

path(fresno,seattle).
path(fresno,albany).
path(fresno,boston).
path(seattle,omaha).
path(seattle,dallas).
path(omaha,albany).
path(omaha,atlanta).
path(albany,seattle).
path(albany,dallas).
path(atlanta,boston).
path(atlanta,dallas).
path(atlanta,albany).
path(dallas,seattle).
path(dallas,albany).

route(A,B,Route) :- direction(A,B,[A],Q), reverse(Q,Route).

direction(A,B,P,[B|P]) :- path(A,B).

direction(A,B,Visited,Route) :- path(A,C), C == B, +member(C,Visited), direction(C,B,[C|Visited],Route).

Related Questions

Navigate

• Browse (All)
• Browse G
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.