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Question 12867: Minimum Positive Separation Proves Finite-Space Completeness

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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R0024-12867 · q-20261014-advance-20261027-r03-complete-metric-space-0017

Original question and givens

Use the complete qualified finite metric table=[[0, 7, 9, 10], [7, 0, 12, 13], [9, 12, 0, 15], [10, 13, 15, 0]] on Fin(4)={0,…,3}, with at least two points for this minimum-positive-distance protocol. Completeness quantifies over every Cauchy sequence and requires a limit in this same space, not merely an ambient space. Testing finitely many sequences or terms is insufficient. Give (n,min_positive_distance,epsilon=min_positive_distance forces every Cauchy tail to be constant,complete?).

  • G001 — Use the complete qualified finite metric table=[[0, 7, 9, 10], [7, 0, 12, 13], [9, 12, 0, 15], [10, 13, 15, 0]] on Fin(4)={0,…,3}, with at least two points for this minimum-positive-distance protocol. Completeness quantifies over every Cauchy sequence and requires a limit in this same space, not merely an ambient space. Testing finitely many sequences or terms is insufficient. Give (n,min_positive_distance,epsilon=min_positive_distance forces every Cauchy tail to be constant,complete?).

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

carrier Fin(4);complete nonnegative integer metric candidate=[[0, 7, 9, 10], [7, 0, 12, 13], [9, 12, 0, 15], [10, 13, 15, 0]]

After

zero iff equal=Yes;symmetric=Yes

Conditions: none

First qualify nonnegativity,diagonal/off-diagonal separation and symmetry on the entire table,not only queried cells.At least two points is a premise of this minimum-positive-distance protocol,not a claim that a singleton is incomplete.

Step identifiers and dependencies

Rule: complete_metric_separation_and_symmetry · Uses: G001

S002 · implies

Before

endpoints=[0, 0];direct distance=0;all intermediate labels=[0, 1, 2, 3]

After

all two-leg distances=[0, 14, 18, 20];direct<=every two-leg=Yes

Conditions: none

For each ordered endpoint pair inspect every intermediate point.All triangle obligations must hold;this complete finite audit is not a few sampled triangles.

Step identifiers and dependencies

Rule: complete_metric_all_triangle_intermediates · Uses: G001, S001

S003 · implies

Before

endpoints=[0, 1];direct distance=7;all intermediate labels=[0, 1, 2, 3]

After

all two-leg distances=[7, 7, 21, 23];direct<=every two-leg=Yes

Conditions: none

For each ordered endpoint pair inspect every intermediate point.All triangle obligations must hold;this complete finite audit is not a few sampled triangles.

Step identifiers and dependencies

Rule: complete_metric_all_triangle_intermediates · Uses: G001, S002

S004 · implies

Before

endpoints=[0, 2];direct distance=9;all intermediate labels=[0, 1, 2, 3]

After

all two-leg distances=[9, 19, 9, 25];direct<=every two-leg=Yes

Conditions: none

For each ordered endpoint pair inspect every intermediate point.All triangle obligations must hold;this complete finite audit is not a few sampled triangles.

Step identifiers and dependencies

Rule: complete_metric_all_triangle_intermediates · Uses: G001, S003

S005 · implies

Before

endpoints=[0, 3];direct distance=10;all intermediate labels=[0, 1, 2, 3]

After

all two-leg distances=[10, 20, 24, 10];direct<=every two-leg=Yes

Conditions: none

For each ordered endpoint pair inspect every intermediate point.All triangle obligations must hold;this complete finite audit is not a few sampled triangles.

Step identifiers and dependencies

Rule: complete_metric_all_triangle_intermediates · Uses: G001, S004

S006 · implies

Before

endpoints=[1, 0];direct distance=7;all intermediate labels=[0, 1, 2, 3]

After

all two-leg distances=[7, 7, 21, 23];direct<=every two-leg=Yes

Conditions: none

For each ordered endpoint pair inspect every intermediate point.All triangle obligations must hold;this complete finite audit is not a few sampled triangles.

Step identifiers and dependencies

Rule: complete_metric_all_triangle_intermediates · Uses: G001, S005

S007 · implies

Before

endpoints=[1, 1];direct distance=0;all intermediate labels=[0, 1, 2, 3]

After

all two-leg distances=[14, 0, 24, 26];direct<=every two-leg=Yes

Conditions: none

For each ordered endpoint pair inspect every intermediate point.All triangle obligations must hold;this complete finite audit is not a few sampled triangles.

Step identifiers and dependencies

Rule: complete_metric_all_triangle_intermediates · Uses: G001, S006

S008 · implies

Before

endpoints=[1, 2];direct distance=12;all intermediate labels=[0, 1, 2, 3]

After

all two-leg distances=[16, 12, 12, 28];direct<=every two-leg=Yes

Conditions: none

For each ordered endpoint pair inspect every intermediate point.All triangle obligations must hold;this complete finite audit is not a few sampled triangles.

Step identifiers and dependencies

Rule: complete_metric_all_triangle_intermediates · Uses: G001, S007

S009 · implies

Before

endpoints=[1, 3];direct distance=13;all intermediate labels=[0, 1, 2, 3]

After

all two-leg distances=[17, 13, 27, 13];direct<=every two-leg=Yes

Conditions: none

For each ordered endpoint pair inspect every intermediate point.All triangle obligations must hold;this complete finite audit is not a few sampled triangles.

Step identifiers and dependencies

Rule: complete_metric_all_triangle_intermediates · Uses: G001, S008

S010 · implies

Before

endpoints=[2, 0];direct distance=9;all intermediate labels=[0, 1, 2, 3]

After

all two-leg distances=[9, 19, 9, 25];direct<=every two-leg=Yes

Conditions: none

For each ordered endpoint pair inspect every intermediate point.All triangle obligations must hold;this complete finite audit is not a few sampled triangles.

Step identifiers and dependencies

Rule: complete_metric_all_triangle_intermediates · Uses: G001, S009

S011 · implies

Before

endpoints=[2, 1];direct distance=12;all intermediate labels=[0, 1, 2, 3]

After

all two-leg distances=[16, 12, 12, 28];direct<=every two-leg=Yes

Conditions: none

For each ordered endpoint pair inspect every intermediate point.All triangle obligations must hold;this complete finite audit is not a few sampled triangles.

Step identifiers and dependencies

Rule: complete_metric_all_triangle_intermediates · Uses: G001, S010

S012 · implies

Before

endpoints=[2, 2];direct distance=0;all intermediate labels=[0, 1, 2, 3]

After

all two-leg distances=[18, 24, 0, 30];direct<=every two-leg=Yes

Conditions: none

For each ordered endpoint pair inspect every intermediate point.All triangle obligations must hold;this complete finite audit is not a few sampled triangles.

Step identifiers and dependencies

Rule: complete_metric_all_triangle_intermediates · Uses: G001, S011

S013 · implies

Before

endpoints=[2, 3];direct distance=15;all intermediate labels=[0, 1, 2, 3]

After

all two-leg distances=[19, 25, 15, 15];direct<=every two-leg=Yes

Conditions: none

For each ordered endpoint pair inspect every intermediate point.All triangle obligations must hold;this complete finite audit is not a few sampled triangles.

Step identifiers and dependencies

Rule: complete_metric_all_triangle_intermediates · Uses: G001, S012

S014 · implies

Before

endpoints=[3, 0];direct distance=10;all intermediate labels=[0, 1, 2, 3]

After

all two-leg distances=[10, 20, 24, 10];direct<=every two-leg=Yes

Conditions: none

For each ordered endpoint pair inspect every intermediate point.All triangle obligations must hold;this complete finite audit is not a few sampled triangles.

Step identifiers and dependencies

Rule: complete_metric_all_triangle_intermediates · Uses: G001, S013

S015 · implies

Before

endpoints=[3, 1];direct distance=13;all intermediate labels=[0, 1, 2, 3]

After

all two-leg distances=[17, 13, 27, 13];direct<=every two-leg=Yes

Conditions: none

For each ordered endpoint pair inspect every intermediate point.All triangle obligations must hold;this complete finite audit is not a few sampled triangles.

Step identifiers and dependencies

Rule: complete_metric_all_triangle_intermediates · Uses: G001, S014

S016 · implies

Before

endpoints=[3, 2];direct distance=15;all intermediate labels=[0, 1, 2, 3]

After

all two-leg distances=[19, 25, 15, 15];direct<=every two-leg=Yes

Conditions: none

For each ordered endpoint pair inspect every intermediate point.All triangle obligations must hold;this complete finite audit is not a few sampled triangles.

Step identifiers and dependencies

Rule: complete_metric_all_triangle_intermediates · Uses: G001, S015

S017 · implies

Before

endpoints=[3, 3];direct distance=0;all intermediate labels=[0, 1, 2, 3]

After

all two-leg distances=[20, 26, 30, 0];direct<=every two-leg=Yes

Conditions: none

For each ordered endpoint pair inspect every intermediate point.All triangle obligations must hold;this complete finite audit is not a few sampled triangles.

Step identifiers and dependencies

Rule: complete_metric_all_triangle_intermediates · Uses: G001, S016

S018 · implies

Before

all off-diagonal positive distances=[7, 9, 10, 7, 12, 13, 9, 12, 15, 10, 13, 15]

After

minimum positive distance delta=7>0

Conditions: none

A finite nonempty list of positive distances has a positive minimum.This is the space-wide scale for the universal Cauchy certificate,not a threshold guessed from a sequence.

Step identifiers and dependencies

Rule: finite_metric_positive_minimum_separation · Uses: G001, S017

S019 · implies

Before

arbitrary Cauchy sequence in Fin(4);choose epsilon=delta=7>0

After

some N has every m,k>=N with d(x_m,x_k)<7;minimum separation forces x_m=x_k

Conditions: none

Apply the Cauchy definition at epsilon=delta to obtain N.Distinct points have distance at least delta,whereas every tail pair has distance strictly below delta.Thus all tail terms equal x_N.

Step identifiers and dependencies

Rule: every_Cauchy_sequence_eventually_constant · Uses: G001, S018

S020 · implies

Before

all tail terms equal x_N;typed sequence guarantees x_N in Fin(4)

After

for every positive eta,all k>=N have distance(x_k,x_N)=0<eta;limit belongs to same space

Conditions: none

The common tail value already belongs to the original space.For any positive eta,the same N gives zero distance.Hence every Cauchy sequence has an internal limit:completeness,not one successful sequence or a limit only in an ambient space.

Step identifiers and dependencies

Rule: finite_completeness_quantifier_and_internal_limit · Uses: G001, S019

Reverse checks

  • S020 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S019 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S018 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S017 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S016 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S015 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S014 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S013 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S012 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S011 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S010 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S009 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • 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

(4, 7, epsilon=min_positive_distance forces every Cauchy tail to be constant, Yes)

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: c810ff393a6198d1c7e05104ccaec54c3c616c073e6d2c3ff02042fa3c3fa567
  • candidate record SHA-256: af289546834fcf41af5c17e4263d4ed253d2e9d107169f326218c392a3d688f3
  • semantic review receipt SHA-256: 1c8f6c2c6c75852cb93c08235684ce9f32ebe86065c58c693a04257e772c2d35
  • question-first witness SHA-256: 05fd764b5f9f7fff6185003efe576d87632f6daf40606ac3839a7feafe4f80d8
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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