LispForum

Discuss and learn Lisp programming of all dialects

This is a read-only archive of lispforum.com. The forum was locked to new users and posts and is preserved here as static HTML from a database snapshot taken on 2019-09-07.

can we search 2 lists at a time?

7 posts · 2213 views

prathyuguduri
#1
When writing dolist could we check 2 lists, if there is no match in the first list then it should go to the second list. And also in dolist could we append to the list that we are checking?

(setq KB '((or a b) (or not c a) (or not b f) (or not d b) (or c d) (or not c e) (or not f g) (or not e f) (not g)))
The first time sos is (not g), It compares with the rest (reverse kb). so it finds a match 6 times. But if I change the order of kb, then Error: In - of (NIL 1) arguments should be of type NUMBER.

But i need to search the kb until I find a match. How to implement this?

Sorry for too many questions. Hope you can help me. Thanks.
Jasper
#2

Re: can we search 2 lists at a time?

Did you see this? I have no idea if that is near your question, but those NOTs and ORs seem to imply it.

It is better to refer not to the variables, but to what they are/mean? Or in terms of a function having certain inputs, and what it is to output? I dubbed KB to be called clause; a combination of (OR ..) true if test on one succeed,(returning first one) (AND ...) true only if test on all succeeds, (NOT ...) true if none of the tests succeed. But i am not sure this is what you want.
nuntius Administrator
#3

Re: can we search 2 lists at a time?

prathyuguduri, could you post the code you have developed? Both Jasper and I posted solutions to what we think you want.

As for checking two lists, you can either check them one at a time; or check (append list1 list2).
prathyuguduri
#4

Re: can we search 2 lists at a time?

(defun process (kb)
(let* ((sos (first (last KB)))
         (soslist (list sos))
		 (clauses (rest (reverse kb)))
         (pred1 (first (last (butlast kb))))
		 (notpos (- (position (second sos) pred1)  1)))

      (let ((pred nil))
        (dolist (clause clauses)
            (when (or (search (list (second sos)) clause)
			(search (list (first sos)) clause))
            (setq pred clause)
			(cond ((= (length sos) 1)  (setq notpos (- (position (first sos) pred) 1)))
                 	             (t (setq notpos (- (position (second sos) pred) 1))))
			(print pred)		
		(cond ((and (equal (length sos) 2)
		(member (second sos) pred)
		(not (equal(nth notpos pred) 'not))) 
		(setq output (remove (second sos) pred))
		(setq output (rest output))
		(setq soslist (append (list output) soslist))
		(setq sos output)
		(nconc clauses (list sos))
		(setq pred1 (first (rest clauses))))
           
		((and (equal (length sos) 1)
          (member (first sos) pred)
		  (equal(nth notpos pred) 'not))
		(setq output (remove-at pred (+ notpos 1)))
		(setq output (remove (first sos) output))
		(setq output (rest output))
		(setq soslist (append (list output) soslist))
		(setq sos output)
		(nconc clauses (list sos))
		(setq pred1 (first (rest clauses)))
		(print sos))

		(t (print "Found contradiction!")))))

)))

Last edited by prathyuguduri on , edited 1 time in total.

prathyuguduri
#5

Re: can we search 2 lists at a time?

@Jasper

Sorry but I don't understand your function completely. What is the "about" that you are using. I don't use "and". And you are comparing only and, or & not. I need to compare the symbols also, in the process I get new elements that I need to append to the list and search in them also until i get a null when i resolve(i.e a (f) & (not f) which should give nil) and then I stop the function.
Jasper
#6

Re: can we search 2 lists at a time?

Essentially(for default TEST), it assigns a true/false value based on a symbol(about) and clause. If the clause is (OR &rest rest) then it returns true only if one or more of the elements of REST os equal to the symbol, or one of the clauses returns true. Similarly for AND, where all of them must be true, and NOT where all of them must be false. Some examples:
(clause-says 'a 'a) ;-> EQL so true
(clause-says 'a '(or b c d)) ; none of them is A, false.
(clause-says 'a '(not c d)) ; none of them is A, true
(clause-says 'a '(or (not a) (and b c d))) ;False
dlweinreb
#7

Re: can we search 2 lists at a time?

I'm not sure I understand what's going on here, but if you want dolist to iterate over list a, and then if it's still iterating, iterate over list b, you can usually do:

(dolist (var (append list-1 list-2))
.. body ..)