Relational-CLPQ

!!! This library currently does not work for properly constraining Prolog variables rationally !!!

A Prolog pack built on top of CLPFD that allows reasoning about the rational numbers.

To-do:

• More robust testing strategy (Limit Value Analysis);
• Implementing logical (and, or, ...) operators;
• Implementing domain/membership operators.
• Implementing other arithmetic operators (^, mod, rem, min, max,...).

Installation

To install the relational-clpq library, type the following in the SWI-Prolog shell:

? - pack_install('relational_clpq').
  true.

or, alternatively, you can install directly from this github repo:

?- pack_install('https://github.com/LuizFBR/Relational-CLPQ.git').
  true.

Examples

Comparison of rational numbers:

1 ?- 10 :=: 10 .
true.

The following example shows clpfd's purity (two-way relation) in action:

2 ?- (10 + X) / Y :=: Z .
clpfd: #=(10+ #(X), #(_A)),
clpfd: #=(#(Z)* #(Y), #(_A)) .

3 ?- 1/2 :=<: 1/2 .
true ;
false.

3 ?- 1/2 :=<: 1/4 .
false.

List of all comparison constraints:

Operator	Meaning
Expr1 :=: Expr2	Expr1 equals Expr2
Expr1 :\=: Expr2	Expr1 is not equal to Expr2
Expr1 :>=: Expr2	Expr1 is greater than or equal to Expr2
Expr1 :=<: Expr2	Expr1 is less than or equal to Expr2
Expr1 :>: Expr2	Expr1 is greater than Expr2
Expr1 :<: Expr2	Expr1 is less than Expr2

Importing

Import this module with

:- use_module(library(relational_clpq)).

Dependencies

This library depends on Markus Triskas' clpfd library:

https://www.swi-prolog.org/man/clpfd.html