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Question 6776: Factorial Window Product and Empty-Window Eligibility

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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R0012-06776 · q-20261010-advance-20261014-r05-factorial-0026

Original question and givens

N begins at 0, F(0)=0!=1, and factorials use exact integer arithmetic, not floating point. 0≤lo=0≤hi=0≤64. Give (hi!/lo!, factor indices lo+1 through hi, is the window empty?).

  • G001 — N begins at 0, F(0)=0!=1, and factorials use exact integer arithmetic, not floating point. 0≤lo=0≤hi=0≤64. Give (hi!/lo!, factor indices lo+1 through hi, is the window empty?).

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

N includes0;F(0)=1;F(j)=j·F(j−1)

After

exact integer products,not floating values or a permutation proof

Conditions: none

Use empty product1 and integer factor multiplication,retaining large values exactly.This finite recurrence audit is not a general proof of permutation counting.

Step identifiers and dependencies

Rule: exact_factorial_protocol · Uses: G001

S002 · implies

Before

lo=0;hi=0;window factors=[]

After

hi!/lo! is the product of exactly these factors

Conditions: none

The positive integer lo! permits cancellation of the common prefix;when lo=hi,no factors remain and the quotient is1.

Step identifiers and dependencies

Rule: factorial_positive_prefix_cancellation · Uses: G001, S001

Reverse checks

  • 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

(1, [], 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: 737252ff00aaa55a8af9037e6063ca3e06ba68bffe166975c4d7bb99550b6f34
  • candidate record SHA-256: d3157fb5ce0edf921cfce9bf724018580ea81018a2e8d65d9a9f927786078564
  • semantic review receipt SHA-256: 90dbc494b2d34ef51f412dcff63cfcc1a2215d038bff71f38f5dded4c64faf00
  • question-first witness SHA-256: b72a3b8bcf10f584396e0dd5198c657b0934a71864e5a3fa6321d7a613aef9f9
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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