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Question 6914: Ordered Fraction Differences and Endpoint Check

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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R0012-06914 · q-20261011-advance-20261015-r01-fraction-0039

Original question and givens

Use legal integer fraction representations with nonzero original denominators; negative denominators are allowed. Representation and value remain distinct. Four ordered values=[-1/-3, 0/1, 1/2, 14/2]. Give (three following-minus-previous differences, their sum, last−first, are those last two results equal?); do not sort.

  • G001 — Use legal integer fraction representations with nonzero original denominators; negative denominators are allowed. Representation and value remain distinct. Four ordered values=[-1/-3, 0/1, 1/2, 14/2]. Give (three following-minus-previous differences, their sum, last−first, are those last two results equal?); do not sort.

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

original integer numerator/denominator representations;original denominators nonzero

After

representation and rational value are distinct data

Conditions: none

Negative denominators are valid,but reduced values do not replace original representations.Candidate algorithms about raw numerators/denominators must use those raw data.This finite audit is not a general proof of quotient well-definedness.

Step identifiers and dependencies

Rule: fraction_representation_value_scope · Uses: G001

S002 · calculation

Before

ordered adjacent difference0 := sub(0, 1/3)

After

ordered adjacent difference0 = -1/3

Conditions: none

Subtract the preceding value from the next in original order,without sorting or deleting repeats.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S001

S003 · calculation

Before

ordered adjacent difference1 := sub(1/2, 0)

After

ordered adjacent difference1 = 1/2

Conditions: none

Subtract the preceding value from the next in original order,without sorting or deleting repeats.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S002

S004 · calculation

Before

ordered adjacent difference2 := sub(7, 1/2)

After

ordered adjacent difference2 = 13/2

Conditions: none

Subtract the preceding value from the next in original order,without sorting or deleting repeats.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S003

S005 · calculation

Before

adjacent difference chain sum := sum(-1/3, 1/2, 13/2)

After

adjacent difference chain sum = 20/3

Conditions: none

Add all three signed adjacent differences.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S004

S006 · calculation

Before

direct final minus initial := sub(7, 1/3)

After

direct final minus initial = 20/3

Conditions: none

Separately subtract initial from final value to audit the endpoint difference.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S005

S007 · implies

Before

ordered values=[1/3, 0/1, 1/2, 7/1];differences=[-1/3, 1/2, 13/2]

After

chain sum=20/3;direct endpoint difference=20/3

Conditions: none

The intermediate terms cancel in(v1−v0)+(v2−v1)+(v3−v2),retaining direction.This is not a difference chain of a sorted value set.

Step identifiers and dependencies

Rule: ordered_fraction_telescope · Uses: G001, S006

Reverse checks

  • 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 — Recompute direct final minus initial with exact rational arithmetic, not rounded decimals.
  • S005 · premise_and_result_audit — Recompute adjacent difference chain sum with exact rational arithmetic, not rounded decimals.
  • S004 · premise_and_result_audit — Recompute ordered adjacent difference2 with exact rational arithmetic, not rounded decimals.
  • S003 · premise_and_result_audit — Recompute ordered adjacent difference1 with exact rational arithmetic, not rounded decimals.
  • S002 · premise_and_result_audit — Recompute ordered adjacent difference0 with exact rational arithmetic, not rounded decimals.
  • S001 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.

Result

([-1/3, 1/2, 13/2], 20/3, 20/3, 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: 91b0eb102e653bc4ade100b096c5354f055416afa7451363d4f504c83567ecdb
  • candidate record SHA-256: 250036312afce657b24244a7941f2c8985ec24f01cdc07e4173e754e0688f60b
  • semantic review receipt SHA-256: 90dbc494b2d34ef51f412dcff63cfcc1a2215d038bff71f38f5dded4c64faf00
  • question-first witness SHA-256: b72a3b8bcf10f584396e0dd5198c657b0934a71864e5a3fa6321d7a613aef9f9
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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