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Question 34176: Exact Ordered Selection Count

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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R0067-34176 · q-20260930-r06-permutation-exact-count-0001

Original question and givens

Select k=0 objects in order, without replacement or repetition, from n=0 distinct objects. The empty selection counts once. Find P(0,0).

  • G001 — Select k=0 objects in order, without replacement or repetition, from n=0 distinct objects. The empty selection counts once. Find P(0,0).

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 = [qf-permutation-exact-count, [k, n, operation]]

After

derived = [permutation, no-invented-domain]

Conditions: none

Check THIS bank’s keys/operation/domain:legacy table underscores,MOD50 local hyphens;permissive BASE data acquires no unknown-field restriction.Keep Number.isInteger and SAFE source guards distinct,while preserving ORIGINAL JSON number representations.

Step identifiers and dependencies

Rule: R67_SOURCE_specific_keys_operation_domain_and_numeric_bank · Uses: G001

S002 · implies

Before

source roles = [0, 0]

After

derived = [[], 1]

Conditions: none

Choose ordered positions from n DISTINCT objects WITHOUT replacement.Position i has n−i+1 choices.For k=0,the empty selection counts ONCE and the product starts at1.THIS bank permits n≤200,not another bank’s32/64 cap.

Step identifiers and dependencies

Rule: Selection_DISTINCT_no_replacement_order_and_EMPTY_convention · Uses: G001, S001

S003 · implies

Before

source roles = [0, 0]

After

derived = [1]

Conditions: none

The multiplication principle combines ALL k position counts,giving P(n,k)=n!/(n−k)!.This is a count,not probability.The empty product is1 and derived BigInts are not truncated to SAFE.

Step identifiers and dependencies

Rule: Selection_ALL_ordered_choices_falling_product · Uses: G001, S002

Reverse checks

  • S003 · premise_and_result_audit — Reverse-audit THIS step against the ORIGINAL roles,complete premises and field order.Distinguish implication from equivalence;preserve originals,English,MKOs,ASTs and review states.Finite checks are not independent review or general formal proof.
  • S002 · premise_and_result_audit — Reverse-audit THIS step against the ORIGINAL roles,complete premises and field order.Distinguish implication from equivalence;preserve originals,English,MKOs,ASTs and review states.Finite checks are not independent review or general formal proof.
  • S001 · premise_and_result_audit — Reverse-audit THIS step against the ORIGINAL roles,complete premises and field order.Distinguish implication from equivalence;preserve originals,English,MKOs,ASTs and review states.Finite checks are not independent review or general formal proof.

Result

1

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: b70506823be44adde13915068572f85a08ead8680c64b9b8049ea61aff9143fe
  • candidate record SHA-256: 3fa4295aca560f0c2c177efec3c9214863930f59787cdaef8f4dd7c78e93f608
  • semantic review receipt SHA-256: c89efa383b67bb2cf25bcf16160b9f5f614bbe5e5e791f4d7f58234d17a3371c
  • question-first witness SHA-256: 12766d451c5375842b4fc2843ae94807ec55f15763a916558026912a13873d57
  • Lean: NOT_RUN · human review: NOT_PERFORMED
Same-source full JSON