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Probably the first appearance of the 3-fractions puzzle in the constraints literature is [schulte2004finite].

The following paper shows how a basic model of the 3-fractions puzzle can be improved automatically [frisch2001extensions].

Using hand-reformulation, the following paper discusses how different using symmetry-breaking schemes on the 3-fractions puzzle, followed by the derivation of implied constraints, can lead to models of varying quality [frisch2004symmetry].

The following paper investigates the numerical issues arising when the number of fractions grows and two new CP models that exploit the integer factorization of the fractions’ denominators [malapert2017puzzle].

The note [codish2018sat] describes a SAT encoding for the n-fractions puzzle for which a SAT solver found new solutions for some of the remaining open instances of this problem.

Only the 44-fractions remains open when combining the most recent results of [malapert2017puzzle] and [codish2018sat]. Other n-fractions have been found or proven infeasible.

[codish2018sat]
Michael Codish
A SAT Encoding for the n-Fractions Problem
CoRR, 2018

[schulte2004finite]
Christian Schulte and Gert Smolka
Finite Domain Constraint Programming in Oz. A Tutorial.
Available at www. mozart-oz. org, 2004

[frisch2004symmetry]
Alan M Frisch, Christopher Jefferson, and Ian Miguel
Symmetry breaking as a prelude to implied constraints: A constraint modelling pattern
ECAI, 171, 2004

[frisch2001extensions]
Alan Frisch, Ian Miguel, and Toby Walsh
Extensions to proof planning for generating implied constraints
In Proceedings of Calculemus-01, 2001

[malapert2017puzzle]
Arnaud Malapert and Julien Provillard
Puzzle—Solving the n-Fractions Puzzle as a Constraint Programming Problem
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