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Question 7270: Two Typed Codomain Candidates and Their Preimages

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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R0013-07270 · q-20261011-advance-20261015-r03-domain-codomain-range-0045

Original question and givens

Fin(5)={0,…,4} is the source and Fin(3)={0,…,2} the codomain; complete typed images=[0, 0, 0, 0, 1] are indexed from 0. All entries must be typed, even unused ones. Ordered codomain candidates=[0, 1]. Give (candidate-type eligibility, preimage index lists or outside-codomain, sizes or outside-codomain). An outside value is not a legal empty preimage.

  • G001 — Fin(5)={0,…,4} is the source and Fin(3)={0,…,2} the codomain; complete typed images=[0, 0, 0, 0, 1] are indexed from 0. All entries must be typed, even unused ones. Ordered codomain candidates=[0, 1]. Give (candidate-type eligibility, preimage index lists or outside-codomain, sizes or outside-codomain). An outside value is not a legal empty preimage.

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

declared types Fin(5)→Fin(3);0-based source labels

After

domain,codomain and actual range remain distinct

Conditions: none

Fin(0) is empty;a complete total table is not a partial program function,and its actual range need not equal its declared codomain.This audits finite data,not general infinite-set theorems.

Step identifiers and dependencies

Rule: typed_domain_codomain_data_scope · Uses: G001

S002 · implies

Before

source index=0∈Fin(5)

After

image[0]=0∈Fin(3)

Conditions: none

First type-check every cell of the complete original table,not only cells queried later.

Step identifiers and dependencies

Rule: typed_complete_original_table_row · Uses: G001, S001

S003 · implies

Before

source index=1∈Fin(5)

After

image[1]=0∈Fin(3)

Conditions: none

First type-check every cell of the complete original table,not only cells queried later.

Step identifiers and dependencies

Rule: typed_complete_original_table_row · Uses: G001, S002

S004 · implies

Before

source index=2∈Fin(5)

After

image[2]=0∈Fin(3)

Conditions: none

First type-check every cell of the complete original table,not only cells queried later.

Step identifiers and dependencies

Rule: typed_complete_original_table_row · Uses: G001, S003

S005 · implies

Before

source index=3∈Fin(5)

After

image[3]=0∈Fin(3)

Conditions: none

First type-check every cell of the complete original table,not only cells queried later.

Step identifiers and dependencies

Rule: typed_complete_original_table_row · Uses: G001, S004

S006 · implies

Before

source index=4∈Fin(5)

After

image[4]=1∈Fin(3)

Conditions: none

First type-check every cell of the complete original table,not only cells queried later.

Step identifiers and dependencies

Rule: typed_complete_original_table_row · Uses: G001, S005

S007 · implies

Before

target candidate=0;inside Fin(3)=Yes

After

preimage=[0, 1, 2, 3];size/status=4

Conditions: none

A legal but unhit codomain value has empty preimage of size0.An outside-codomain candidate is not a legal empty-preimage query in this typed interface.

Step identifiers and dependencies

Rule: typed_preimage_codomain_guard · Uses: G001, S006

S008 · implies

Before

target candidate=1;inside Fin(3)=Yes

After

preimage=[4];size/status=1

Conditions: none

A legal but unhit codomain value has empty preimage of size0.An outside-codomain candidate is not a legal empty-preimage query in this typed interface.

Step identifiers and dependencies

Rule: typed_preimage_codomain_guard · Uses: G001, S007

Reverse checks

  • S008 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • 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 — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S005 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S004 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • 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 — Check against the original data and this step's premises; a one-way implication is not an equivalence.

Result

([Yes, Yes], [[0, 1, 2, 3], [4]], [4, 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: cf21bdbce13426ad8e82ea0c13a3c81d0a73ea268c85e685de2f923bf314b23f
  • candidate record SHA-256: 6a18bc61e4259528ae2d54126b8510875a87490e08e562b1554b536bd9227005
  • semantic review receipt SHA-256: e89fc6d4a50a4a7fc942c6c8939a92f835e30105a9a5850e37dd198f31c1ed59
  • question-first witness SHA-256: 0e1039f4cf022bf35af4e5531651c9a2b7ca7a5fdacac34fb1e4bcd9a81f6299
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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