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Question 7542: Declared Affine Model and Zero-Point Linearity Guard

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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← Question derivation index · Original question batch

R0014-07542 · q-20261012-advance-20261016-r03-linear-transformation-0092

Original question and givens

Use the explicitly declared matrix model on all R²→R² with column vectors. Finite test values do not prove an arbitrary function linear; the zero matrix defines a linear map. Declare F(v)=Mv+b on all R², with M=[[1, 0], [0, 2]], v=[4, 1], b=[0, 0]. Give (Mv, Mv+b, F(0)=b, is this declared affine model linear?).

  • G001 — Use the explicitly declared matrix model on all R²→R² with column vectors. Finite test values do not prove an arbitrary function linear; the zero matrix defines a linear map. Declare F(v)=Mv+b on all R², with M=[[1, 0], [0, 2]], v=[4, 1], b=[0, 0]. Give (Mv, Mv+b, F(0)=b, is this declared affine model linear?).

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

M=[[1, 0], [0, 2]];v=[4, 1]

After

declared R2 matrix model;finite values are not a test of an arbitrary function

Conditions: none

The declared matrix model Mv gives a linear map on all R² by distributivity.The listed finite evaluations do not prove an arbitrary function linear.The zero map is linear;nonzero values or invertibility are not required.

Step identifiers and dependencies

Rule: declared_linear_model_scope · Uses: G001

S002 · calculation

Before

Mv[0] term0 := mul(1, 4)

After

Mv[0] term0 = 4

Conditions: none

Multiply the specified scalar and component at this position;do not substitute an inner product or entrywise matrix product.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S001

S003 · calculation

Before

Mv[0] term1 := mul(0, 1)

After

Mv[0] term1 = 0

Conditions: none

Multiply the specified scalar and component at this position;do not substitute an inner product or entrywise matrix product.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S002

S004 · calculation

Before

Mv[0] row sum := sum(4, 0)

After

Mv[0] row sum = 4

Conditions: none

Add the already aligned component or position,without mixing coordinates.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S003

S005 · calculation

Before

Mv[1] term0 := mul(0, 4)

After

Mv[1] term0 = 0

Conditions: none

Multiply the specified scalar and component at this position;do not substitute an inner product or entrywise matrix product.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S004

S006 · calculation

Before

Mv[1] term1 := mul(2, 1)

After

Mv[1] term1 = 2

Conditions: none

Multiply the specified scalar and component at this position;do not substitute an inner product or entrywise matrix product.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S005

S007 · calculation

Before

Mv[1] row sum := sum(0, 2)

After

Mv[1] row sum = 2

Conditions: none

Add the already aligned component or position,without mixing coordinates.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S006

S008 · calculation

Before

Mv+b[0] := sum(4, 0)

After

Mv+b[0] = 4

Conditions: none

Add the already aligned component or position,without mixing coordinates.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S007

S009 · calculation

Before

Mv+b[1] := sum(2, 0)

After

Mv+b[1] = 2

Conditions: none

Add the already aligned component or position,without mixing coordinates.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S008

S010 · implies

Before

F(x)=Mx+b;M=[[1, 0], [0, 2]];b=[0, 0]

After

F(0)=[0, 0];linear model qualified=Yes

Conditions: none

Necessity:a linear map has F(0)=0,so b must be zero.Sufficiency:when b=0 the declared model reduces to Mx,whose additivity and homogeneity follow from distributivity.This is not a claim that a zero-value test proves an arbitrary function linear.

Step identifiers and dependencies

Rule: affine_zero_obstruction_and_sufficiency · Uses: G001, S009

Reverse checks

  • S010 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S009 · premise_and_result_audit — Recompute Mv+b[1] with exact rational arithmetic, not rounded decimals.
  • S008 · premise_and_result_audit — Recompute Mv+b[0] with exact rational arithmetic, not rounded decimals.
  • S007 · premise_and_result_audit — Recompute Mv[1] row sum with exact rational arithmetic, not rounded decimals.
  • S006 · premise_and_result_audit — Recompute Mv[1] term1 with exact rational arithmetic, not rounded decimals.
  • S005 · premise_and_result_audit — Recompute Mv[1] term0 with exact rational arithmetic, not rounded decimals.
  • S004 · premise_and_result_audit — Recompute Mv[0] row sum with exact rational arithmetic, not rounded decimals.
  • S003 · premise_and_result_audit — Recompute Mv[0] term1 with exact rational arithmetic, not rounded decimals.
  • S002 · premise_and_result_audit — Recompute Mv[0] term0 with exact rational arithmetic, not rounded decimals.
  • S001 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.

Result

([4, 2], [4, 2], [0, 0], 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: 0e71dcc4644bc8490543b3acd010475a45e8837ef86d351fb1ba33c7a1dfa42d
  • candidate record SHA-256: 103c98c64e9e08191f720b1c6d541c59e1ddc76377da1f70b8aa586cbef2d500
  • semantic review receipt SHA-256: 23ba8196e85a09c03add0a87f96bec5d67a00dc648d1d68eef89101525b41a77
  • question-first witness SHA-256: 17d59afc327b7cb8b6e588686d6dc1abbccd384d8ba32b8c046652f96821d705
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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