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Question 8128: Bijection Guard before Constructing Both Inverse Compositions

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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R0015-08128 · q-20261012-advance-20261017-r02-inverse-function-0003

Original question and givens

Use the complete total map Fin(1)={0,…,0}→Fin(1) with images=[0] in source-index order. Validate every image in the declared codomain first. Equal finite cardinalities do not make the given map bijective. Give (images, bijectivity, inverse table or not-an-inverse-function, g∘f values or not-evaluated, f∘g values or not-evaluated). Do not confuse inverse functions with reciprocal function values.

  • G001 — Use the complete total map Fin(1)={0,…,0}→Fin(1) with images=[0] in source-index order. Validate every image in the declared codomain first. Equal finite cardinalities do not make the given map bijective. Give (images, bijectivity, inverse table or not-an-inverse-function, g∘f values or not-evaluated, f∘g values or not-evaluated). Do not confuse inverse functions with reciprocal function values.

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=1;m=1;images=[0]

After

complete typed total map;inverse is not reciprocal

Conditions: none

Validate the whole original total table first.Equal finite cardinalities do not ensure this particular table is bijective,and a zero function value does not prohibit an inverse.

Step identifiers and dependencies

Rule: inverse_typed_map_scope · Uses: G001

S002 · implies

Before

target=0;original images=[0]

After

fiber=[0];unique=Yes

Conditions: none

Scan every original input and list all preimages of this declared target.An empty or multiple-preimage fiber cannot supply a cell of a total inverse.

Step identifiers and dependencies

Rule: inverse_complete_target_fiber · Uses: G001, S001

S003 · implies

Before

n=1;m=1;fibers=[[0]]

After

bijective=Yes

Conditions: none

For the already total map,exactly one preimage per codomain target is equivalent to bijectivity.The empty-to-empty map qualifies;checking n=m alone is insufficient.

Step identifiers and dependencies

Rule: inverse_bijection_gate · Uses: G001, S002

S004 · implies

Before

unique fibers=[[0]]

After

inverse table=[0]

Conditions: none

Construct the inverse table in codomain order from each target's unique preimage.

Step identifiers and dependencies

Rule: construct_inverse_only_after_bijection · Uses: G001, S003

S005 · implies

Before

gof:input=0;f(input)=0;g=[0]

After

g(f(input))=0;identity target=0;matches=Yes

Conditions: none

Follow f to a codomain label,then read the typed g table.This direction has a different domain from the other composition.

Step identifiers and dependencies

Rule: inverse_composition_lookup · Uses: G001, S004

S006 · implies

Before

fog:input=0;g(input)=0;f=[0]

After

f(g(input))=0;identity target=0;matches=Yes

Conditions: none

Start the reverse composition independently at every original codomain target;g∘f values cannot replace f∘g values.

Step identifiers and dependencies

Rule: inverse_composition_lookup · Uses: G001, S005

S007 · implies

Before

gof=[0];fog=[0]

After

left identity=Yes;right identity=Yes

Conditions: none

Check each identity over its own complete index set.A one-sided identity does not imply the other;conditions over an empty index set are true.

Step identifiers and dependencies

Rule: inverse_two_identities_separate · 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 — 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

([0], Yes, [0], [0], [0])

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: ac43c97a7a680c48999a818deb710fa858f561c7ed2b2b702371c00890d86b8c
  • candidate record SHA-256: 06aa838effbe21d427a8e9a9a3ca33ad63034e2a6e946f2bcee951d461c95b63
  • semantic review receipt SHA-256: 6ecad9d909199221a07e923f87425e80b3bdec3eed46fe5910d04fca694cae18
  • question-first witness SHA-256: e8f00458977a09493b5f9f05ab9e6feec72debaf4c7d1c609d1fc95900a35a1b
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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