<*philosophy of science, logic*> an informal method for
solving problems in the absence of an algorithm for
formal proof. Heuristics typically have only restricted
applicability and limited likelihood of success but, as George
Polya showed, contribute significantly to our understanding
of mathematical truths.
Recommended Reading: George Polya, How to Solve It (Princeton,
1971); Gerd Gigerenzer amd Peter M. Todd, Simple Heuristics That
Make Us Smart (Oxford, 1999); and George Polya, Mathematics and
Plausible Reasoning (Princeton, 1990).

[A Dictionary of Philosophical Terms and Names]

1. <*PI*> A rule of thumb, simplification or educated
guess that reduces or limits the search for solutions in
domains that are difficult and poorly understood. Unlike
algorithms, heuristics do not guarantee optimal, or even
feasible, solutions and are often used with no theoretical
guarantee.

[What is a "feasible solution"?]

2. <*algorithm*> approximation algorithm.

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