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Question 26076: An Explicit Smaller Cover Refutes Minimum Cardinality

On this page
  1. Original question and givens
  2. Definition and scope
  3. Step-by-step derivation
  4. Reverse checks
  5. Result
  6. This question review and source binding

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R0051-26076 · q-20261015-advance-20261115-r06-minimum-vertex-cover-0026

Original question and givens

Use complete unique vertices=[v0, v1, v2, v3] and loop-free duplicate-free undirected edges=[[v0, v1], [v1, v2], [v2, v3]], candidate cover=[v0, v1, v2, v3]. An edge needs at least one selected endpoint. Preserve source canonical subset order. Give (candidate, cover, candidate_size, minimum_size, smaller_cover, minimum, certificate).

  • G001 — Use complete unique vertices=[v0, v1, v2, v3] and loop-free duplicate-free undirected edges=[[v0, v1], [v1, v2], [v2, v3]], candidate cover=[v0, v1, v2, v3]. An edge needs at least one selected endpoint. Preserve source canonical subset order. Give (candidate, cover, candidate_size, minimum_size, smaller_cover, minimum, certificate).

Definition and scope

Use the original question domain, assumptions and cited MKO definitions. This item has second-context mathematical and bilingual review, with the model, answer and every arithmetic step independently recomputed from the original parameters; the source question remains a candidate.

Step-by-step derivation

S001 · implies

Before

source roles = [mincover-nonminimum-witness]

After

derived = [[candidate, cover, candidate_size, minimum_size, smaller_cover, minimum, certificate]]

Conditions: none

List the full source field order without JavaScript.Original modes select contract6/4/6/6 and IVT8/7/8 roles,without padding or answer-shape inference.

Step identifiers and dependencies

Rule: source_ordered_fields_without_JS · Uses: G001

S002 · implies

Before

source roles = [[v0, v1, v2, v3], [[v0, v1], [v1, v2], [v2, v3]], [v0, v1, v2, v3]]

After

derived = [[v0, v1, v2, v3], [[v0, v1], [v1, v2], [v2, v3]], [v0, v1, v2, v3]]

Conditions: none

The carrier is nonempty with at most12 vertices;sort endpoints by UTF16 then edge families in English.Reject loops/reversed duplicates.An omitted candidate stays null,not an invented empty candidate.

Step identifiers and dependencies

Rule: Mincover_complete_simple_graph_UTF16_English_and_optional_candidate · Uses: G001, S001

S003 · implies

Before

source roles = [[v0, v1, v2, v3], [[v0, v1], [v1, v2], [v2, v3]], 16]

After

derived = [[5, 6, 7, 10, 11, 13, 14, 15], [[0, 0], [1, 1], [2, 2], [3, 2], [4, 0], [8, 0], [9, 1], [12, 0]], [[v0, v2], [v1, v2], [v0, v1, v2], [v1, v3], [v0, v1, v3], [v0, v2, v3], [v1, v2, v3], [v0, v1, v2, v3]], [0, 0, 3, 4, 1], 2, [[v0, v2], [v1, v2], [v1, v3]]]

Conditions: none

Audit every mask against every edge,retaining the first uncovered-edge refutation for each failure and every accepted set in source order.Zero smaller-size counts give a lower bound and actual minimum covers attain it.Keep all ties in numeric-mask order,not English/size order.

Step identifiers and dependencies

Rule: Mincover_ALL_masks_acceptance_refutations_ALLcovers_ALLminimizers · Uses: G001, S002

S004 · implies

Before

source roles = [[v0, v1, v2, v3], [[v0, v1], [v1, v2], [v2, v3]]]

After

derived = [[[[v0, v1], Yes], [[v1, v2], Yes], [[v2, v3], Yes]], 4, 2, [v0, v2]]

Conditions: none

First qualify an actual candidate cover.The smaller witness is the first minimum from the complete source list,not an arbitrary small set.

Step identifiers and dependencies

Rule: Mincover_actual_candidate_complete_cover_and_smaller_witness · Uses: G001, S003

Reverse checks

  • S004 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S003 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S002 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S001 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.

Result

([v0, v1, v2, v3], Yes, 4, 2, [v0, v2], No, explicit_smaller_cover_refutes_minimum_status)

The full substitutions and premise checks give the original answer; source identity,format and status are unchanged.

This question review and source binding

Review date: 2026-10-26

Original questions, answers, step expressions, numeric ASTs and historical records are retained. Source candidate labels remain historical and are not overwritten as formal proof.

Source hashes and review receipts
  • input commit: 0f7be61e2c22317a4075561dc822c87d881a50db
  • original question SHA-256: e9356db80c39d695015d8d114c44354acb3dd1a0d5b419771063470f20727c80
  • candidate record SHA-256: 023757297a53eb9531c970c4b7469ff23c013a8c774ef742359176885be938b2
  • semantic review receipt SHA-256: 90df1e889242e9afdf01e068788ee8500ef366ffcfc0496e30a6800de32631c3
  • question-first witness SHA-256: ae1e849608590ca856c9f3b6911ba58e3bf53c608eb7369606192a770f48bd5c
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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