Lab 9: Prolog

1. Evaluate your TA first.
2. How to run Prolog?
   • On any lab machine, run SWI-Prolog from /usr/csshare/bin/pl
   • Alternatively, add /usr/csshare/bin to your path and run pl
3. Prolog mode for Emacs
   • Download prolog.el
   • Save prolog.el to ~/share/emacs/
   • Add the following to your ~/.emacs

     (setq load-path (append (list 
                                   "~/share/emacs"
                                   )
                              load-path))
     (autoload 'run-prolog "prolog" "Start a Prolog sub-process." t)
     (autoload 'prolog-mode "prolog" "Major mode for editing Prolog programs." t)
     (autoload 'mercury-mode "prolog" "Major mode for editing Mercury programs." t)
     (setq prolog-system 'swi)
     (setq auto-mode-alist (append '(("\\.pro$" . prolog-mode)
                                     ("\\.m$" . mercury-mode))
                                    auto-mode-alist))
       

   • Alternatively, download my .emacs example.
   • Press C-c C-b to run your editing code with Prolog.
4. Prolog Exercises
   • Define a predicate max(X,Y,Z) that takes numbers X and Y and unifies Z with the maxnum of the two.
   • Define a predicate maxlist(L,M) that takes a list L of numbers and unifies M with the maximum number in the list. The predicate should fail if the list L is empty.
   • Define a predicate ordered(L) that succeeds if and only if the list of numbers L is in non-decreasing order - each element is less than or equal to the next.
   • Define the isMember predicate so that isMember(X,Y) says that element X is a member of set Y.
   • Define the isUnion predicate so that isUnion(X,Y,Z) says that the union of X and Y is Z. Do not use predefined list predicates.
   • Define the isIntersection predicate so that isIntersection(X,Y,Z) says that the intersection of X and Y is Z.
   • Define the longinitseq predicate so that longinitseq(L,X,N) is provable iff the longest sequence of consecutive elements in L that are the same as X and begin with the first element has length N. For example, longinitseq([a,b,b],H,N) should return H=a,N=1.
   • Define the longseq predicate so that longseq(L,X,N) is provable iff the longest sequence of consecutive elements in L that are the same as X has length N. For example, longseq([a,b,b,a,a,a,c],H,N) should return H=a,N=3; H=b,N=2; and H=c,N=1.

References:

• Prolog mode for Emacs