CODEWITHSUNDEEP
clingo
Fatimat Opeyemi
Fatimat Opeyemi

Reputation: 1

Answer Set Programming Beginner

I am a beginner in Answer Set Programming and completely new to clingo. I tried the facts and constraints below on nurses shift on clingo, but I am not getting any model and clingo not flagging any error. I keep getting UNSAT. What am I not doing right?

nurselimits(x, min, max). 
worklimits(min, max).
daylimits(x, t, min, max).
x(morning; afternoon; night; off; leave).
x(1..5).


day(1..28).
days(28).
nurse(1..40).
shift(1, morning, 8).
shift(2, afternoon, 14).
shift(3, night, 20).
shift(4, off, 0).
shift(5, leave, 10).
nurselimits(1,6,9).
nurselimits(2,6,9).
nurselimits(3,4,7).
daylimits(1,8,6,9).
daylimits(2,8,6,9).
daylimits(3,8,5,10).
worklimits(132,228).



 {assign(N, X, D) : shift(X, Name, H), X != 4, X != 5} = 1:- nurse(N), day(D).



:- day(D), #count{N : assign(N, X, D)} > max, nurselimits(x, min, max).
:- day(D), #count{N : assign(N, X, D)} < min, nurselimits(x, min, max).

:- nurse(N), #sum{H, D : assign(N, X, D), shift(X, Name, H)} > max, worklimits(min, max).
:- nurse(N), #sum{H, D : assign(N, X, D), shift(X, Name, H)} < min, worklimits(min, max).


:- nurse(N), assign(N, X1, D), assign(N, X2, D+1), X2 < X1 , X1 <= 3.

:- nurse(N), day(D), days(DAYS), D <= DAYS-21, 
   #count{D1 : assign(N, 4, D1), D1 >= D, D1 <= D+21} = 1.


:- nurse(N), #count{D: assign(N, X, D)} > max, daylimits(x, t, min, max).

:- nurse(N), #count{D: assign(N, X, D)} < min, daylimits(x, t, min, max).

Upvotes: 0

Views: 355

Answers (2)

user1747134
user1747134

Reputation: 2472

In this code

nurselimits(x, min, max). 
worklimits(min, max).
daylimits(x, t, min, max).
x(morning; afternoon; night; off; leave).
x(1..5).

There are several problems. The symbols x, min, max, t. Are all non-numerical symbolic constants, much like morning, afternoon,etc. That is probably unintended, unless you are substituting them using the -c command line option. Certainly, the x in nurselimits has nothing to do with the x(1..5) in your code, which also seems unintended. Also, the constant min is the same symbolic value in nurselimits, worklimits and daylimits. Perhaps you wanted it to be variable instead?

Upvotes: 1

nicole.ts
nicole.ts

Reputation: 1

You should remove first three lines and add #show (e.g. #show assign/3.) of any predicate you want to see in the answer sets.

Upvotes: 0

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