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Question 4421: Two Relative-Complement Computations

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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R0007-04421 · q-20261008-advance-20261010-r02-set-operations-0071

Original question and givens

Finite integer sets A=[0] and B=[-1, 20]; repeated elements count once. The explicit universe is U=[-20, -1, 0, 1, 20], with A,B⊆U. Give (U\(A∪B), (U\A)∩(U\B)), each sorted increasingly.

  • G001 — Finite integer sets A=[0] and B=[-1, 20]; repeated elements count once. The explicit universe is U=[-20, -1, 0, 1, 20], with A,B⊆U. Give (U\(A∪B), (U\A)∩(U\B)), each sorted increasingly.

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

raw A=[0];raw B=[-1, 20]

After

A=[0];B=[-1, 20]

Conditions: none

Deduplicate and numerically sort integer sets;repetition and input order do not change membership.The original lists remain retained.

Step identifiers and dependencies

Rule: finite_set_extensionality · Uses: G001

S002 · implies

Before

element=-20

After

in A=No;in B=No

Conditions: none

Record membership on both sides for each element;these Boolean values determine the set operations without duplicate counting.

Step identifiers and dependencies

Rule: finite_set_membership_row · Uses: G001, S001

S003 · implies

Before

element=-1

After

in A=No;in B=Yes

Conditions: none

Record membership on both sides for each element;these Boolean values determine the set operations without duplicate counting.

Step identifiers and dependencies

Rule: finite_set_membership_row · Uses: G001, S002

S004 · implies

Before

element=0

After

in A=Yes;in B=No

Conditions: none

Record membership on both sides for each element;these Boolean values determine the set operations without duplicate counting.

Step identifiers and dependencies

Rule: finite_set_membership_row · Uses: G001, S003

S005 · implies

Before

element=1

After

in A=No;in B=No

Conditions: none

Record membership on both sides for each element;these Boolean values determine the set operations without duplicate counting.

Step identifiers and dependencies

Rule: finite_set_membership_row · Uses: G001, S004

S006 · implies

Before

element=20

After

in A=No;in B=Yes

Conditions: none

Record membership on both sides for each element;these Boolean values determine the set operations without duplicate counting.

Step identifiers and dependencies

Rule: finite_set_membership_row · Uses: G001, S005

S007 · implies

Before

explicit U=[-20, -1, 0, 1, 20];U\A=[-20, -1, 1, 20];U\B=[-20, 0, 1]

After

U\(A∪B)=[-20, 1];(U\A)∩(U\B)=[-20, 1]

Conditions: none

Both expressions require membership in neither A nor B;complements are relative only to the declared U,not arbitrary outside integers.

Step identifiers and dependencies

Rule: relative_demorgan_complements · 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

([-20, 1], [-20, 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: 5cbc4863beb44c1b956d0b256fbddcfd16a417c0d61be4c147b8b1da38a3e996
  • candidate record SHA-256: 3ebe7f103d1b9a9ddd498a60805af1312f7b69987526869ad5231cb2bdc52fbb
  • semantic review receipt SHA-256: faf0582c0184613e6fae207374056133eae600883a29c67d8438113bbe3c485a
  • question-first witness SHA-256: 4b283b6ff424b1d22caa36f3552b0fa21b1b66a0a883d7cbe9cedc8dd77b2e42
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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