Assignment 3

CSc 8710 Deductive Databases and Logic Programming
Fall 1999
Programming Assignment #3
October 18, 1999 (Monday)

Consider the following Prolog query:

  trip(L,S,E) :- leg(L,S,E).
  trip(L,S,E) :- leg(L,S,I), trip(L,I,E). 
  trip(L,S,E) :- interchange(I,L,M), trip(L,S,I), trip(M,I,E).

  query(X) :- trip(blue,suwanee,X).

where the base predicates are defined as follows:

leg(L,S,T) is true if it there is a train on line L which leaves station S and arrives at the next station T with no intermediate stops. For example, on MARTA, the following may be some of the instances:

  leg(ne,doraville,chamblee).
  leg(ne,chamblee,doraville).
  leg(ne,chamblee,brookhaven).
  leg(ne,brookhaven,chamblee).
  leg(ne,brookhaven,lenox).
  leg(ne,lenox,brookhaven).
  leg(n,medical-center,dunwoody).
  leg(n,dunwoody,medical-center).

interchange(S,L,M) is true if it is possible to change from line L to line M in station S. Instances in MARTA would be:
```
  interchange(lindbergh,n,ne).
  interchange(lindbergh,ne,n).
  interchange(fivepoints,n,e).
  interchange(fivepoints,e,n).
  interchange(fivepoints,ne,e).
  interchange(fivepoints,e,ne).
```
Write a program in Pro*C or Pro*C++ or Java (using JDBC or SQLJ database access) to answer the query. You should prompt the user for the two constants in the query (line and station values).