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Question 15234: Compute Distance in the Norm Induced by This Positive-Definite Form

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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← Question derivation index · Original question batch

R0029-15234 · q-20261014-advance-20261030-r02-real-hilbert-space-0059

Original question and givens

Use the same real plane with symmetric positive-definite matrix G=[[10, 2], [2, 5]] and inner product <x,y>=x^T G y. Its induced norm and metric belong to that same carrier, not to unrelated structures. Left vector=[-4, 1], right vector=[4, -2]. Give (left,right,left_minus_right,squared_distance,symbolic_square_root).

  • G001 — Use the same real plane with symmetric positive-definite matrix G=[[10, 2], [2, 5]] and inner product <x,y>=x^T G y. Its induced norm and metric belong to that same carrier, not to unrelated structures. Left vector=[-4, 1], right vector=[4, -2]. Give (left,right,left_minus_right,squared_distance,symbolic_square_root).

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

Hilbert Gram diagonal product := mul(10, 5)

After

Hilbert Gram diagonal product = 50

Conditions: none

Compute exactly from original roles and established intermediates,retaining denominators,strict guards,indices and signs.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001

S002 · calculation

Before

Hilbert Gram off-diagonal product := mul(2, 2)

After

Hilbert Gram off-diagonal product = 4

Conditions: none

Compute exactly from original roles and established intermediates,retaining denominators,strict guards,indices and signs.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S001

S003 · calculation

Before

Hilbert Gram determinant := sub(50, 4)

After

Hilbert Gram determinant = 46

Conditions: none

Compute exactly from original roles and established intermediates,retaining denominators,strict guards,indices and signs.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S002

S004 · calculation

Before

Hilbert completing-square slope := div(2, 10)

After

Hilbert completing-square slope = 1/5

Conditions: none

Compute exactly from original roles and established intermediates,retaining denominators,strict guards,indices and signs.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S003

S005 · calculation

Before

Hilbert completing-square positive residual := div(46, 10)

After

Hilbert completing-square positive residual = 23/5

Conditions: none

Compute exactly from original roles and established intermediates,retaining denominators,strict guards,indices and signs.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S004

S006 · implies

Before

complete real carrier R^2;Gram matrix=[[10, 2], [2, 5]];a=10>0;det=46>0;dimension declaration=2

After

x^T M x=10*(x0+(1/5)*x1)^2+(23/5)*x1^2;zero only at x=0

Conditions: none

Symmetry and positive principal minors give positivity for every real vector by completing the square,not just testing the displayed vectors.The triangular transformation is invertible,so this inner-product norm is equivalent to the coordinate norm on R².A Cauchy sequence has convergent coordinates and its limit remains in this same R².

Step identifiers and dependencies

Rule: hilbert_same_complete_matrix_positive_inner_product · Uses: G001, S005

S007 · calculation

Before

Hilbert distance coordinate0 difference := sub(-4, 4)

After

Hilbert distance coordinate0 difference = -8

Conditions: none

Compute exactly from original roles and established intermediates,retaining denominators,strict guards,indices and signs.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S006

S008 · calculation

Before

Hilbert distance coordinate1 difference := sub(1, -2)

After

Hilbert distance coordinate1 difference = 3

Conditions: none

Compute exactly from original roles and established intermediates,retaining denominators,strict guards,indices and signs.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S007

S009 · calculation

Before

Hilbert distance coefficient(0,0) times left coordinate := mul(10, -8)

After

Hilbert distance coefficient(0,0) times left coordinate = -80

Conditions: none

Compute exactly from original roles and established intermediates,retaining denominators,strict guards,indices and signs.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S008

S010 · calculation

Before

Hilbert distance term(0,0) := mul(-80, -8)

After

Hilbert distance term(0,0) = 640

Conditions: none

Compute exactly from original roles and established intermediates,retaining denominators,strict guards,indices and signs.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S009

S011 · calculation

Before

Hilbert distance coefficient(0,1) times left coordinate := mul(2, -8)

After

Hilbert distance coefficient(0,1) times left coordinate = -16

Conditions: none

Compute exactly from original roles and established intermediates,retaining denominators,strict guards,indices and signs.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S010

S012 · calculation

Before

Hilbert distance term(0,1) := mul(-16, 3)

After

Hilbert distance term(0,1) = -48

Conditions: none

Compute exactly from original roles and established intermediates,retaining denominators,strict guards,indices and signs.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S011

S013 · calculation

Before

Hilbert distance coefficient(1,0) times left coordinate := mul(2, 3)

After

Hilbert distance coefficient(1,0) times left coordinate = 6

Conditions: none

Compute exactly from original roles and established intermediates,retaining denominators,strict guards,indices and signs.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S012

S014 · calculation

Before

Hilbert distance term(1,0) := mul(6, -8)

After

Hilbert distance term(1,0) = -48

Conditions: none

Compute exactly from original roles and established intermediates,retaining denominators,strict guards,indices and signs.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S013

S015 · calculation

Before

Hilbert distance coefficient(1,1) times left coordinate := mul(5, 3)

After

Hilbert distance coefficient(1,1) times left coordinate = 15

Conditions: none

Compute exactly from original roles and established intermediates,retaining denominators,strict guards,indices and signs.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S014

S016 · calculation

Before

Hilbert distance term(1,1) := mul(15, 3)

After

Hilbert distance term(1,1) = 45

Conditions: none

Compute exactly from original roles and established intermediates,retaining denominators,strict guards,indices and signs.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S015

S017 · calculation

Before

Hilbert distance complete bilinear sum := sum(640, -48, -48, 45)

After

Hilbert distance complete bilinear sum = 589

Conditions: none

Compute exactly from original roles and established intermediates,retaining denominators,strict guards,indices and signs.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S016

S018 · implies

Before

left=[-4, 1];right=[4, -2];same induced metric on R^2;squared norm=589

After

distance=sqrt(589)

Conditions: none

Subtract coordinates,expand the same Gram quadratic form completely,and take its nonnegative square root.Keep the original sqrt display rather than switching to Euclidean distance or a different simplification.

Step identifiers and dependencies

Rule: hilbert_distance_nonnegative_root_same_metric · Uses: G001, S017

Reverse checks

  • 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 — Recompute Hilbert distance complete bilinear sum with exact rational arithmetic, not rounded decimals.
  • S016 · premise_and_result_audit — Recompute Hilbert distance term(1,1) with exact rational arithmetic, not rounded decimals.
  • S015 · premise_and_result_audit — Recompute Hilbert distance coefficient(1,1) times left coordinate with exact rational arithmetic, not rounded decimals.
  • S014 · premise_and_result_audit — Recompute Hilbert distance term(1,0) with exact rational arithmetic, not rounded decimals.
  • S013 · premise_and_result_audit — Recompute Hilbert distance coefficient(1,0) times left coordinate with exact rational arithmetic, not rounded decimals.
  • S012 · premise_and_result_audit — Recompute Hilbert distance term(0,1) with exact rational arithmetic, not rounded decimals.
  • S011 · premise_and_result_audit — Recompute Hilbert distance coefficient(0,1) times left coordinate with exact rational arithmetic, not rounded decimals.
  • S010 · premise_and_result_audit — Recompute Hilbert distance term(0,0) with exact rational arithmetic, not rounded decimals.
  • S009 · premise_and_result_audit — Recompute Hilbert distance coefficient(0,0) times left coordinate with exact rational arithmetic, not rounded decimals.
  • S008 · premise_and_result_audit — Recompute Hilbert distance coordinate1 difference with exact rational arithmetic, not rounded decimals.
  • S007 · premise_and_result_audit — Recompute Hilbert distance coordinate0 difference with exact rational arithmetic, not rounded decimals.
  • 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 — Recompute Hilbert completing-square positive residual with exact rational arithmetic, not rounded decimals.
  • S004 · premise_and_result_audit — Recompute Hilbert completing-square slope with exact rational arithmetic, not rounded decimals.
  • S003 · premise_and_result_audit — Recompute Hilbert Gram determinant with exact rational arithmetic, not rounded decimals.
  • S002 · premise_and_result_audit — Recompute Hilbert Gram off-diagonal product with exact rational arithmetic, not rounded decimals.
  • S001 · premise_and_result_audit — Recompute Hilbert Gram diagonal product with exact rational arithmetic, not rounded decimals.

Result

([-4, 1], [4, -2], [-8, 3], 589, sqrt(589))

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: c9cf7df1f34828cfb1c8994d22e5cd4bc3b6afcaa9520e49cf455eeccdb59538
  • candidate record SHA-256: b3045b33f12174fe45c3ecb278e7714b33a1b62139a367e1628870fced02e9a1
  • semantic review receipt SHA-256: 8c0ef6ca8c5ba2754e41f30c2b32bcb757756152d97421f7396d39038c11f725
  • question-first witness SHA-256: c7920a0ff8e724b7e566ebbda30b31d8087c136974b62f8c760fbd26ab816117
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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