# The techniques

> The technique shelf: the algorithms and pruning ideas that recur in every serious Eternity II solver, each with what it is, what it costs, and what it actually bought when measured on this puzzle.

- Canonical page (with interactive figures/demos): https://eternity2.dev/research/build/techniques/
- Updated: 2026-07-21
- Source: Constraint satisfaction problem (Wikipedia): the umbrella framework — https://en.wikipedia.org/wiki/Constraint_satisfaction_problem

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The technique shelf: the algorithms and pruning ideas that recur in every
serious Eternity II solver, each with what it is, what it costs, and what it
actually bought when measured on this puzzle.

New here, or want the whole territory at once? Start with
[a map of every known approach](/research/build/approaches-map): every
family of attack on one page, what each reached, and where it walls out.

The [solver catalogue](/research/build/solvers) shows how record engines
assemble these parts; the [dead ends](/research/build/dead-ends) page lists
the techniques that sounded just as good and didn't survive contact.

## Related

- [How the record solvers search](https://eternity2.dev/research/build/solvers) — How the solvers that hold the records actually search. They are all, at heart, depth-first backtrackers; what separates them is the order they try things and how they bend the rules near the end.
- [Dead ends](https://eternity2.dev/research/build/dead-ends) — Approaches we tried that look promising and don't move the needle on Eternity II, written down with what we found so you can spend your time elsewhere.