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Question 13438: A Named-Norm Distance Is Not a Completeness Proof

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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R0025-13438 · q-20261014-advance-20261028-r03-real-banach-space-0063

Original question and givens

Use the explicit real coordinate space R^n of dimension=3, with the named norm=l1, limited to l1 or linfinity. A Banach certificate must bind the carrier, vector operations, norm, the metric induced by that same norm, and completeness of that same space. The named finite-dimensional real normed-space theorem is a universal mathematical premise, not a new Lean receipt or sampled-sequence proof. No Hilbert, compactness or arbitrary infinite-dimensional conclusion is inferred. left=[0, 2, -2], right=[0, 2, -2]. Give (norm_name,left,right,left−right,distance,distance_evaluation_not_completeness_proof).

  • G001 — Use the explicit real coordinate space R^n of dimension=3, with the named norm=l1, limited to l1 or linfinity. A Banach certificate must bind the carrier, vector operations, norm, the metric induced by that same norm, and completeness of that same space. The named finite-dimensional real normed-space theorem is a universal mathematical premise, not a new Lean receipt or sampled-sequence proof. No Hilbert, compactness or arbitrary infinite-dimensional conclusion is inferred. left=[0, 2, -2], right=[0, 2, -2]. Give (norm_name,left,right,left−right,distance,distance_evaluation_not_completeness_proof).

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 · calculation

Before

Banach coordinate distance difference coordinate0 := sub(0, 0)

After

Banach coordinate distance difference coordinate0 = 0

Conditions: none

Compute exactly from original roles and established intermediates,retaining coefficients,coordinates,order and signs.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001

S002 · calculation

Before

Banach coordinate distance difference coordinate1 := sub(2, 2)

After

Banach coordinate distance difference coordinate1 = 0

Conditions: none

Compute exactly from original roles and established intermediates,retaining coefficients,coordinates,order and signs.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S001

S003 · calculation

Before

Banach coordinate distance difference coordinate2 := sub(-2, -2)

After

Banach coordinate distance difference coordinate2 = 0

Conditions: none

Compute exactly from original roles and established intermediates,retaining coefficients,coordinates,order and signs.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S002

S004 · implies

Before

Banach coordinate distance:norm=l1;left=[0, 2, -2];right=[0, 2, -2]

After

signed left-right=[0, 0, 0];use same named norm

Conditions: none

Use the same stated norm on the same real coordinate space.The derived difference can exceed original input coordinate bounds and must not be clipped or rejected as a new raw input.

Step identifiers and dependencies

Rule: norm_distance_same_space_and_direction · Uses: G001, S003

S005 · implies

Before

Banach coordinate distance:coordinate=0;signed value=0

After

absolute value=0

Conditions: none

Take each whole coordinate's absolute value while preserving the original signed vector.Do not use a signed maximum.

Step identifiers and dependencies

Rule: named_norm_coordinate_absolute_value · Uses: G001, S004

S006 · implies

Before

Banach coordinate distance:coordinate=1;signed value=0

After

absolute value=0

Conditions: none

Take each whole coordinate's absolute value while preserving the original signed vector.Do not use a signed maximum.

Step identifiers and dependencies

Rule: named_norm_coordinate_absolute_value · Uses: G001, S005

S007 · implies

Before

Banach coordinate distance:coordinate=2;signed value=0

After

absolute value=0

Conditions: none

Take each whole coordinate's absolute value while preserving the original signed vector.Do not use a signed maximum.

Step identifiers and dependencies

Rule: named_norm_coordinate_absolute_value · Uses: G001, S006

S008 · calculation

Before

Banach coordinate distance l1 sum := sum(0, 0, 0)

After

Banach coordinate distance l1 sum = 0

Conditions: none

Compute exactly from original roles and established intermediates,retaining coefficients,coordinates,order and signs.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S007

S009 · implies

Before

fixed carrier R^3;named norm=l1;distance=0

After

distance_evaluation_not_completeness_proof

Conditions: none

One distance evaluation quantifies over no Cauchy sequences and is not itself a completeness proof.

Step identifiers and dependencies

Rule: Banach_distance_evaluation_not_all_Cauchy_claim · Uses: G001, S008

Reverse checks

  • 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 — Recompute Banach coordinate distance l1 sum with exact rational arithmetic, not rounded decimals.
  • 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 — Recompute Banach coordinate distance difference coordinate2 with exact rational arithmetic, not rounded decimals.
  • S002 · premise_and_result_audit — Recompute Banach coordinate distance difference coordinate1 with exact rational arithmetic, not rounded decimals.
  • S001 · premise_and_result_audit — Recompute Banach coordinate distance difference coordinate0 with exact rational arithmetic, not rounded decimals.

Result

(l1, [0, 2, -2], [0, 2, -2], [0, 0, 0], 0, distance_evaluation_not_completeness_proof)

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: 4ba8d9f42ca47168cbe115fccb80ef3494ac8406b888671e9e8798467ed59afa
  • candidate record SHA-256: c49143bf41859d5d9dc043e0f52c913afcfc86c853c94f9b2a1b2e116a905c75
  • semantic review receipt SHA-256: 0e51c2bf621e6e998415fdd75d260464e625cecd5894a230c9f09553249551c5
  • question-first witness SHA-256: ceb79401a62782c9f7e5ed86afee9b1a71455f799bd24cf485cba7aa8ecaca8a
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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