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Question 11046: Audit lambda without Clipping an Affine Extension

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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R0021-11046 · q-20261013-advance-20261024-r05-finite-convex-combination-0071

Original question and givens

Use a finite nonempty ordered vector list and aligned exact rational weights. Convex weights may be zero but must be nonnegative and sum exactly to 1, not merely approximately. A convex-combination witness establishes its weighted point, not unique coordinates without separate affine independence. left=[8, 0], right=[11, 3], lambda=21/23. Give (left,right,normalized lambda,lambda in [0,1]?,lambda*left+(1−lambda)*right,is this a convex combination?). This audit still computes the affine expression when lambda lies outside [0,1], but both qualification flags must then be No. Use exact rational arithmetic, reduce fractions to positive denominators and omit /1 for integer outputs.

  • G001 — Use a finite nonempty ordered vector list and aligned exact rational weights. Convex weights may be zero but must be nonnegative and sum exactly to 1, not merely approximately. A convex-combination witness establishes its weighted point, not unique coordinates without separate affine independence. left=[8, 0], right=[11, 3], lambda=21/23. Give (left,right,normalized lambda,lambda in [0,1]?,lambda*left+(1−lambda)*right,is this a convex combination?). This audit still computes the affine expression when lambda lies outside [0,1], but both qualification flags must then be No. Use exact rational arithmetic, reduce fractions to positive denominators and omit /1 for integer outputs.

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

two-point complementary weight := sub(1, 21/23)

After

two-point complementary weight = 2/23

Conditions: none

Compute exactly with this step's specified roles,retaining signs,denominators and original pairings.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001

S002 · implies

Before

two-point:raw lambda=[21, 23];lambda=21/23;one-minus-lambda=2/23

After

in_closed_unit_interval=Yes;lambda weights left

Conditions: none

Lambda weights the left endpoint and1−lambda the right.Lambda0 selects right,1 selects left.Outside values still define the affine expression,but not a convex combination;do not clip.

Step identifiers and dependencies

Rule: two_point_direction_and_qualification · Uses: G001, S001

S003 · implies

Before

two-point:ordered vectors=[[8, 0], [11, 3]];aligned weights=[21/23, 2/23]

After

dimension=2;preserve duplicates and order

Conditions: none

Preserve vector order,duplicates and coefficient pairing.Sum every vector's contribution within the same coordinate.

Step identifiers and dependencies

Rule: ordered_vector_weight_pairing · Uses: G001, S002

S004 · calculation

Before

two-point coordinate0 term0 := mul(21/23, 8)

After

two-point coordinate0 term0 = 168/23

Conditions: none

Compute exactly with this step's specified roles,retaining signs,denominators and original pairings.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S003

S005 · calculation

Before

two-point coordinate0 term1 := mul(2/23, 11)

After

two-point coordinate0 term1 = 22/23

Conditions: none

Compute exactly with this step's specified roles,retaining signs,denominators and original pairings.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S004

S006 · calculation

Before

two-point coordinate0 sum := sum(168/23, 22/23)

After

two-point coordinate0 sum = 190/23

Conditions: none

Compute exactly with this step's specified roles,retaining signs,denominators and original pairings.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S005

S007 · calculation

Before

two-point coordinate1 term0 := mul(21/23, 0)

After

two-point coordinate1 term0 = 0

Conditions: none

Compute exactly with this step's specified roles,retaining signs,denominators and original pairings.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S006

S008 · calculation

Before

two-point coordinate1 term1 := mul(2/23, 3)

After

two-point coordinate1 term1 = 6/23

Conditions: none

Compute exactly with this step's specified roles,retaining signs,denominators and original pairings.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S007

S009 · calculation

Before

two-point coordinate1 sum := sum(0, 6/23)

After

two-point coordinate1 sum = 6/23

Conditions: none

Compute exactly with this step's specified roles,retaining signs,denominators and original pairings.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S008

Reverse checks

  • S009 · premise_and_result_audit — Recompute two-point coordinate1 sum with exact rational arithmetic, not rounded decimals.
  • S008 · premise_and_result_audit — Recompute two-point coordinate1 term1 with exact rational arithmetic, not rounded decimals.
  • S007 · premise_and_result_audit — Recompute two-point coordinate1 term0 with exact rational arithmetic, not rounded decimals.
  • S006 · premise_and_result_audit — Recompute two-point coordinate0 sum with exact rational arithmetic, not rounded decimals.
  • S005 · premise_and_result_audit — Recompute two-point coordinate0 term1 with exact rational arithmetic, not rounded decimals.
  • S004 · premise_and_result_audit — Recompute two-point coordinate0 term0 with exact rational arithmetic, not rounded decimals.
  • 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 — Recompute two-point complementary weight with exact rational arithmetic, not rounded decimals.

Result

([8, 0], [11, 3], 21/23, Yes, [190/23, 6/23], 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: dc98e3834e1b69a874b579ac59f692eb55a7a9f9fc3b53904d6728eae5116248
  • candidate record SHA-256: 02a20c0cd6c25b901853761a1b39a83fdb65e4161f00a0a11e5f9f5eb4d1c1f3
  • semantic review receipt SHA-256: 47d23d3735987d68e27733b051bdfa80a3616d44fb223b82bf2e6c8e46d49258
  • question-first witness SHA-256: a857db558000724020d2d5e815cb6bc3e2c9e2933df295bf33eb478d3c695139
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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