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Question 17371: Exhaust the Complete Finite Topology before Certifying Connectedness

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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R0033-17371 · q-20261014-advance-20261103-r05-connected-topological-space-0071

Original question and givens

Use the actual finite carrier Fin(5)={0,…,4} and its complete declared topology=[[], [0], [0, 4], [0, 2, 4], [0, 1, 2, 4], [0, 1, 2, 3, 4]], with subsets in the supplied order. Empty and whole sets, all finite intersections and all unions must belong to this finite topology. Connectedness means absence of a separation into two disjoint nonempty open sets covering this actual carrier, equivalently absence of a nontrivial clopen subset. It is not graph connectivity or a conclusion from selected tests. The empty-space convention here is explicitly the vacuous no-separation convention,not a nonempty ConnectedSpace type. Give (clopen_sets,nontrivial_clopen,connected?,exhaustive_complete_finite_topology), retaining the supplied topology order within both lists.

  • G001 — Use the actual finite carrier Fin(5)={0,…,4} and its complete declared topology=[[], [0], [0, 4], [0, 2, 4], [0, 1, 2, 4], [0, 1, 2, 3, 4]], with subsets in the supplied order. Empty and whole sets, all finite intersections and all unions must belong to this finite topology. Connectedness means absence of a separation into two disjoint nonempty open sets covering this actual carrier, equivalently absence of a nontrivial clopen subset. It is not graph connectivity or a conclusion from selected tests. The empty-space convention here is explicitly the vacuous no-separation convention,not a nonempty ConnectedSpace type. Give (clopen_sets,nontrivial_clopen,connected?,exhaustive_complete_finite_topology), retaining the supplied topology order within both lists.

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

ACTUAL carrier Fin(5);original ordered complete topology=[[], [0], [0, 4], [0, 2, 4], [0, 1, 2, 4], [0, 1, 2, 3, 4]]

After

unique empty/whole opens present;empty carrier allowed;first union failure=null;first intersection failure=null

Conditions: none

The actual n may be0,when empty and whole are the same open rather than two distinct sets.Check canonical subsets and all binary union/intersection obligations;the finite family then handles arbitrary unions.This data fixes the actual space,not a reference label.

Step identifiers and dependencies

Rule: connected_actual_complete_topology_including_empty_carrier · Uses: G001

S002 · implies

Before

original open index=0;open=[];ACTUAL same-carrier complement=[0, 1, 2, 3, 4]

After

complement open=Yes;nonempty proper subset=No;nontrivial clopen obstruction=No

Conditions: none

The original member is open;it is clopen only if its complement is open.A separation obstruction also requires nonemptiness and properness.List all candidates in original topology order;one failed candidate cannot establish connectedness.

Step identifiers and dependencies

Rule: connected_every_actual_open_complement_not_selected_samples · Uses: G001, S001

S003 · implies

Before

original open index=1;open=[0];ACTUAL same-carrier complement=[1, 2, 3, 4]

After

complement open=No;nonempty proper subset=Yes;nontrivial clopen obstruction=No

Conditions: none

The original member is open;it is clopen only if its complement is open.A separation obstruction also requires nonemptiness and properness.List all candidates in original topology order;one failed candidate cannot establish connectedness.

Step identifiers and dependencies

Rule: connected_every_actual_open_complement_not_selected_samples · Uses: G001, S002

S004 · implies

Before

original open index=2;open=[0, 4];ACTUAL same-carrier complement=[1, 2, 3]

After

complement open=No;nonempty proper subset=Yes;nontrivial clopen obstruction=No

Conditions: none

The original member is open;it is clopen only if its complement is open.A separation obstruction also requires nonemptiness and properness.List all candidates in original topology order;one failed candidate cannot establish connectedness.

Step identifiers and dependencies

Rule: connected_every_actual_open_complement_not_selected_samples · Uses: G001, S003

S005 · implies

Before

original open index=3;open=[0, 2, 4];ACTUAL same-carrier complement=[1, 3]

After

complement open=No;nonempty proper subset=Yes;nontrivial clopen obstruction=No

Conditions: none

The original member is open;it is clopen only if its complement is open.A separation obstruction also requires nonemptiness and properness.List all candidates in original topology order;one failed candidate cannot establish connectedness.

Step identifiers and dependencies

Rule: connected_every_actual_open_complement_not_selected_samples · Uses: G001, S004

S006 · implies

Before

original open index=4;open=[0, 1, 2, 4];ACTUAL same-carrier complement=[3]

After

complement open=No;nonempty proper subset=Yes;nontrivial clopen obstruction=No

Conditions: none

The original member is open;it is clopen only if its complement is open.A separation obstruction also requires nonemptiness and properness.List all candidates in original topology order;one failed candidate cannot establish connectedness.

Step identifiers and dependencies

Rule: connected_every_actual_open_complement_not_selected_samples · Uses: G001, S005

S007 · implies

Before

original open index=5;open=[0, 1, 2, 3, 4];ACTUAL same-carrier complement=[]

After

complement open=Yes;nonempty proper subset=No;nontrivial clopen obstruction=No

Conditions: none

The original member is open;it is clopen only if its complement is open.A separation obstruction also requires nonemptiness and properness.List all candidates in original topology order;one failed candidate cannot establish connectedness.

Step identifiers and dependencies

Rule: connected_every_actual_open_complement_not_selected_samples · Uses: G001, S006

S008 · implies

Before

ALL actual clopen sets=[[], [0, 1, 2, 3, 4]];ALL nontrivial clopen sets=[]

After

a nontrivial clopen S gives separation(S,X minus S);a separation by disjoint nonempty opens gives such a clopen S;actual connected iff no such set

Conditions: none

A proper nonempty clopen and its open complement separate the carrier.Conversely the two opens in a separation are complements,so either is nontrivial clopen.Exhausting the complete finite topology therefore excludes every separation.This is not connectivity of an unrelated graph.

Step identifiers and dependencies

Rule: connected_clopen_separation_equivalence_full_finite_exhaustion · Uses: G001, S007

Reverse checks

  • S008 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S007 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S006 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S005 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • 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

([[], [0, 1, 2, 3, 4]], [], Yes, exhaustive_complete_finite_topology)

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: bf480d494dde1c3f10f8f5ced98dbe00ee6a0a924b4a2451d720d3a8ab675874
  • candidate record SHA-256: a252d24c1ae3e0a9611e7a377c3886fe68870ff4b435551f27ab7fa2b488b3fe
  • semantic review receipt SHA-256: 4a0957a15bb33fbe5f663e37a8babf46ab5a291eb5d1dfa3bf9045204cd43ec3
  • question-first witness SHA-256: 22a8506bcfa34c503216083d1a8e813d61aad22dbc81589c0d41089c528a7f93
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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