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Question 26226: The Geometric Tail Bound Controls the Exact Picard Error

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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R0051-26226 · q-20261015-advance-20261116-r01-contraction-mapping-theorem-0051

Original question and givens

Use the complete exact metric matrix=[[0, 1, 3], [1, 0, 2], [3, 2, 0]], aligned mapping=[0, 0, 1] and q=1/2. Qualify nonnegativity, separation, symmetry and every triangle, the entire self-map and every ordered contraction pair. A finite metric space is complete. Start=2, steps=2. Give (orbit, fixed_point, actual_error, geometric_bound, bound_holds, certificate).

  • G001 — Use the complete exact metric matrix=[[0, 1, 3], [1, 0, 2], [3, 2, 0]], aligned mapping=[0, 0, 1] and q=1/2. Qualify nonnegativity, separation, symmetry and every triangle, the entire self-map and every ordered contraction pair. A finite metric space is complete. Start=2, steps=2. Give (orbit, fixed_point, actual_error, geometric_bound, bound_holds, 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 = [contract-fixed-point-bound]

After

derived = [[orbit, fixed_point, actual_error, geometric_bound, bound_holds, 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 = [[[0, 1, 3], [1, 0, 2], [3, 2, 0]]]

After

derived = [3, Yes, Yes, Yes, [[0, 0, 0, 0, 0, Yes], [0, 0, 1, 1, 1, Yes], [0, 0, 2, 3, 3, Yes], [0, 1, 0, 0, 2, Yes], [0, 1, 1, 1, 1, Yes], [0, 1, 2, 3, 3, Yes], [0, 2, 0, 0, 6, Yes], [0, 2, 1, 1, 5, Yes], [0, 2, 2, 3, 3, Yes], [1, 0, 0, 1, 1, Yes], [1, 0, 1, 0, 2, Yes], [1, 0, 2, 2, 4, Yes], [1, 1, 0, 1, 1, Yes], [1, 1, 1, 0, 0, Yes], [1, 1, 2, 2, 2, Yes], [1, 2, 0, 1, 5, Yes], [1, 2, 1, 0, 4, Yes], [1, 2, 2, 2, 2, Yes], [2, 0, 0, 3, 3, Yes], [2, 0, 1, 2, 4, Yes], [2, 0, 2, 0, 6, Yes], [2, 1, 0, 3, 3, Yes], [2, 1, 1, 2, 2, Yes], [2, 1, 2, 0, 4, Yes], [2, 2, 0, 3, 3, Yes], [2, 2, 1, 2, 2, Yes], [2, 2, 2, 0, 0, Yes]], Yes]

Conditions: none

Check every triangle triple,not sampled metric behavior.A nonempty finite metric is complete:trivial for a singleton;otherwise the minimum positive distance delta forces a Cauchy tail with distances<delta to be constant,with limit in X.

Step identifiers and dependencies

Rule: Contraction_COMPLETE_metric_axioms_ALL_triangles_finite_completeness · Uses: G001, S001

S003 · calculation

Before

Contraction ORIGINAL pair0,0 q times distance := mul(1/2, 0)

After

Contraction ORIGINAL pair0,0 q times distance = 0

Conditions: none

Substitute original roles and established intermediates exactly,without rounding;extra teaching identities do not restrict the source domain.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S002

S004 · calculation

Before

Contraction ORIGINAL pair0,1 q times distance := mul(1/2, 1)

After

Contraction ORIGINAL pair0,1 q times distance = 1/2

Conditions: none

Substitute original roles and established intermediates exactly,without rounding;extra teaching identities do not restrict the source domain.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S003

S005 · calculation

Before

Contraction ORIGINAL pair0,2 q times distance := mul(1/2, 3)

After

Contraction ORIGINAL pair0,2 q times distance = 3/2

Conditions: none

Substitute original roles and established intermediates exactly,without rounding;extra teaching identities do not restrict the source domain.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S004

S006 · calculation

Before

Contraction ORIGINAL pair1,0 q times distance := mul(1/2, 1)

After

Contraction ORIGINAL pair1,0 q times distance = 1/2

Conditions: none

Substitute original roles and established intermediates exactly,without rounding;extra teaching identities do not restrict the source domain.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S005

S007 · calculation

Before

Contraction ORIGINAL pair1,1 q times distance := mul(1/2, 0)

After

Contraction ORIGINAL pair1,1 q times distance = 0

Conditions: none

Substitute original roles and established intermediates exactly,without rounding;extra teaching identities do not restrict the source domain.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S006

S008 · calculation

Before

Contraction ORIGINAL pair1,2 q times distance := mul(1/2, 2)

After

Contraction ORIGINAL pair1,2 q times distance = 1

Conditions: none

Substitute original roles and established intermediates exactly,without rounding;extra teaching identities do not restrict the source domain.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S007

S009 · calculation

Before

Contraction ORIGINAL pair2,0 q times distance := mul(1/2, 3)

After

Contraction ORIGINAL pair2,0 q times distance = 3/2

Conditions: none

Substitute original roles and established intermediates exactly,without rounding;extra teaching identities do not restrict the source domain.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S008

S010 · calculation

Before

Contraction ORIGINAL pair2,1 q times distance := mul(1/2, 2)

After

Contraction ORIGINAL pair2,1 q times distance = 1

Conditions: none

Substitute original roles and established intermediates exactly,without rounding;extra teaching identities do not restrict the source domain.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S009

S011 · calculation

Before

Contraction ORIGINAL pair2,2 q times distance := mul(1/2, 0)

After

Contraction ORIGINAL pair2,2 q times distance = 0

Conditions: none

Substitute original roles and established intermediates exactly,without rounding;extra teaching identities do not restrict the source domain.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S010

S012 · implies

Before

source roles = [[0, 0, 1], 1/2, [[0, 1, 3], [1, 0, 2], [3, 2, 0]]]

After

derived = [Yes, Yes, [[0, 0, 0, 0, Yes], [0, 1, 0, 1/2, Yes], [0, 2, 1, 3/2, Yes], [1, 0, 0, 1/2, Yes], [1, 1, 0, 0, Yes], [1, 2, 1, 1, Yes], [2, 0, 1, 3/2, Yes], [2, 1, 1, 1, Yes], [2, 2, 0, 0, Yes]], Yes, [0]]

Conditions: none

Separate self-map,0<=q<1 and all pair inequalities.Nonself maps have empty source pair rows;self maps retain actual pair results even when q-range fails.Array length or samples do not prove global contraction.

Step identifiers and dependencies

Rule: Contraction_selfmap_q_range_ALL_ordered_pairs_separate · Uses: G001, S011

S013 · implies

Before

source roles = [0, 2, [0, 0, 1]]

After

derived = [1, 1]

Conditions: none

Apply the same complete map at every step,retaining the start and all iterates rather than guessing a fixed point from a short prefix.

Step identifiers and dependencies

Rule: Contraction_EACH_Picard_iterate_original_total_map · Uses: G001, S012

S014 · implies

Before

source roles = [1, 1, [0, 0, 1]]

After

derived = [0, 0]

Conditions: none

Apply the same complete map at every step,retaining the start and all iterates rather than guessing a fixed point from a short prefix.

Step identifiers and dependencies

Rule: Contraction_EACH_Picard_iterate_original_total_map · Uses: G001, S013

S015 · implies

Before

source roles = [1/2, [0], 2, [2, 1, 0]]

After

derived = [[3, 1, 0], d(x_(n+k),x_n)<=q^n*(1-q^k)/(1-q)*d(x1,x0), complete limit fixed;two fixed points obey(1-q)d<=0 hence coincide]

Conditions: none

Successive distances shrink by q;the triangle inequality sums the finite geometric tail,making Picard Cauchy.Completeness gives a limit and Lipschitz continuity makes it fixed.Two fixed points satisfy distance<=q*distance,so q<1 forces equality.This pedagogical argument does not label a finite orbit a general formal proof.

Step identifiers and dependencies

Rule: Contraction_GENERAL_geometric_tail_complete_limit_and_unique_fixed · Uses: G001, S014

S016 · implies

Before

(1/2)^2

After

Contraction ORIGINAL q powerN = 1/4

Conditions: none

Evaluate the finite nonnegative-integer power exactly; exponent0 uses the polynomial multiplicative identity.

Step identifiers and dependencies

Rule: integer_power · Uses: G001, S015

S017 · calculation

Before

Contraction strict one minus q := sub(1, 1/2)

After

Contraction strict one minus q = 1/2

Conditions: none

Substitute original roles and established intermediates exactly,without rounding;extra teaching identities do not restrict the source domain.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S016

S018 · calculation

Before

Contraction geometric tail factor := div(1/4, 1/2)

After

Contraction geometric tail factor = 1/2

Conditions: none

Substitute original roles and established intermediates exactly,without rounding;extra teaching identities do not restrict the source domain.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S017

S019 · calculation

Before

Contraction factor times ORIGINAL first-step distance := mul(1/2, 2)

After

Contraction factor times ORIGINAL first-step distance = 1

Conditions: none

Substitute original roles and established intermediates exactly,without rounding;extra teaching identities do not restrict the source domain.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S018

S020 · implies

Before

source roles = [2, 1/2, [2, 1, 0], 0, 2]

After

derived = [0, 1, Yes]

Conditions: none

Let tail length tend to infinity to obtain the error bound.At N0,q^0 is the empty product1,including q0.The source computes powers/division before multiplying first distance;zero distance does not bypass its numeric profile.

Step identifiers and dependencies

Rule: Contraction_actual_error_bound_N0_q0_profile_NOT_shortcircuited · 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 — Recompute Contraction factor times ORIGINAL first-step distance with exact rational arithmetic, not rounded decimals.
  • S018 · premise_and_result_audit — Recompute Contraction geometric tail factor with exact rational arithmetic, not rounded decimals.
  • S017 · premise_and_result_audit — Recompute Contraction strict one minus q with exact rational arithmetic, not rounded decimals.
  • 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 — Recompute Contraction ORIGINAL pair2,2 q times distance with exact rational arithmetic, not rounded decimals.
  • S010 · premise_and_result_audit — Recompute Contraction ORIGINAL pair2,1 q times distance with exact rational arithmetic, not rounded decimals.
  • S009 · premise_and_result_audit — Recompute Contraction ORIGINAL pair2,0 q times distance with exact rational arithmetic, not rounded decimals.
  • S008 · premise_and_result_audit — Recompute Contraction ORIGINAL pair1,2 q times distance with exact rational arithmetic, not rounded decimals.
  • S007 · premise_and_result_audit — Recompute Contraction ORIGINAL pair1,1 q times distance with exact rational arithmetic, not rounded decimals.
  • S006 · premise_and_result_audit — Recompute Contraction ORIGINAL pair1,0 q times distance with exact rational arithmetic, not rounded decimals.
  • S005 · premise_and_result_audit — Recompute Contraction ORIGINAL pair0,2 q times distance with exact rational arithmetic, not rounded decimals.
  • S004 · premise_and_result_audit — Recompute Contraction ORIGINAL pair0,1 q times distance with exact rational arithmetic, not rounded decimals.
  • S003 · premise_and_result_audit — Recompute Contraction ORIGINAL pair0,0 q times distance with exact rational arithmetic, not rounded decimals.
  • 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

([2, 1, 0], 0, 0, 1, Yes, d_xn_fixed_le_qn_over_one_minus_q_times_d_x1_x0)

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: 4a1cd08bb78ff270d8380551166b7abe358cadcfa775b82102d1682f9f750446
  • candidate record SHA-256: d73d4007f1d501262eb621b5f8bf9250f00f7b73a44013589842a91f058aee9e
  • semantic review receipt SHA-256: 90df1e889242e9afdf01e068788ee8500ef366ffcfc0496e30a6800de32631c3
  • question-first witness SHA-256: ae1e849608590ca856c9f3b6911ba58e3bf53c608eb7369606192a770f48bd5c
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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