zipper_algebra: Implement majority-of-three using DNF zipper merge#43
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marcin-rzeznicki wants to merge 3 commits into
Open
zipper_algebra: Implement majority-of-three using DNF zipper merge#43marcin-rzeznicki wants to merge 3 commits into
marcin-rzeznicki wants to merge 3 commits into
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…n the original slice-of-slices version Everything is now expressed in terms of two bounded bitspaces
Introduce zipper_merge_dnf(), a generalized trie merge capable of
evaluating monotone Boolean expressions in Disjunctive Normal Form.
The implementation represents a DNF as:
(Clause0) ∨ (Clause1) ∨ ...
where each Clause is a conjunction of input zippers encoded as a
compact bitmask. This replaces the earlier slice-of-slices approach
with a fixed universe of zippers plus clause membership masks.
Highlights:
* Add Clause<N> newtype for conjunction representation.
* Enforce clause validity at construction time.
* Add clause![] helper macro for ergonomic DNF construction.
* Share zipper traversal across clauses that reference the same input.
* Perform iterative tail descent when all active clauses follow the
same path.
* Dispatch single-clause cases to specialized meet implementations.
* Support arbitrary monotone DNF expressions, including majority and
threshold functions.
Example:
(x ∧ y) ∨ (x ∧ z) ∨ (y ∧ z)
can now be expressed as:
[
clause![0, 1],
clause![0, 2],
clause![1, 2],
]
and evaluated directly via zipper_merge_dnf().
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Author
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@Adam-Vandervorst your recommendations from the call are implemented in 9917e7d and ab62492 |
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This PR adds a
majorityzipper operation, returning values present in at least two of the three inputs.The implementation is expressed directly in terms of the DNF merge engine using the identity:
A value therefore survives iff it is present in at least two operands.
This serves both as a useful operation and as a demonstration of the expressive power of the DNF evaluator. Unlike pairwise merge operators such as
Join,Meet, orSubtract, majority is naturally described as a disjunction of conjunctions, making it a good fit for the new DNF traversal framework.The implementation reuses the existing DNF merge machinery and requires no specialized traversal logic.