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Question 2218: A First-Order Candidate: Grid Residuals and Initial Value

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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R0003-02218 · q-20261013-advance-20261021-r04-initial-value-problem-0068

Original question and givens

Use the integer polynomial candidate with ascending-power coefficients=[5, 0]. Initial data and ODE residuals are separate obligations. Neither a finite grid nor an initial-value match proves existence, uniqueness, a general solution or an identity on an entire interval. Relation y'=p*y+q with p=0, q=0; input grid=[-1, 0, 1], x0=0, required y0=5. Normalize the grid to sorted distinct points. Give (coefficients,p,q,grid,every [x,y,y',y'−p*y−q,zero?] row,x0,y(x0),required y0,initial match?,all grid residuals zero and initial match?).

  • G001 — Use the integer polynomial candidate with ascending-power coefficients=[5, 0]. Initial data and ODE residuals are separate obligations. Neither a finite grid nor an initial-value match proves existence, uniqueness, a general solution or an identity on an entire interval. Relation y'=p*y+q with p=0, q=0; input grid=[-1, 0, 1], x0=0, required y0=5. Normalize the grid to sorted distinct points. Give (coefficients,p,q,grid,every [x,y,y',y'−p*y−q,zero?] row,x0,y(x0),required y0,initial match?,all grid residuals zero and initial match?).

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

candidate polynomial ascending coefficients=[5, 0]

After

initial point=0; required y₀=5

Conditions: none

Retain the polynomial and initial data;the residual grid need not contain the initial point,so evaluate it separately.

Step identifiers and dependencies

Rule: candidate_IVP_data · Uses: G001

S002 · calculation

Before

y′ coefficient at degree0 := mul(1, 0)

After

y′ coefficient at degree0 = 0

Conditions: none

Multiply by the original degree and lower it by1;the constant term differentiates to0.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S001

S003 · implies

Before

initial y ascending coefficients=[5, 0]

After

evaluate at x=0

Conditions: none

Evaluate ascending coefficients by Horner from the highest nonzero term down;ignoring redundant top zero terms changes neither the function nor the retained original list.

Step identifiers and dependencies

Rule: polynomial_evaluation_order · Uses: G001, S002

S004 · implies

Before

y(0)=5; required=5

After

value condition=Yes

Conditions: none

Compare the actual function value at the initial point,not another grid point.

Step identifiers and dependencies

Rule: initial_value_condition · Uses: G001, S003

S005 · implies

Before

[-1, 0, 1]

After

distinct ordered audit grid=[-1, 0, 1]

Conditions: none

Deduplication and sorting fix presentation;every listed distinct point is then audited.

Step identifiers and dependencies

Rule: finite_grid_domain · Uses: G001, S004

S006 · implies

Before

y at-1 ascending coefficients=[5, 0]

After

evaluate at x=-1

Conditions: none

Evaluate ascending coefficients by Horner from the highest nonzero term down;ignoring redundant top zero terms changes neither the function nor the retained original list.

Step identifiers and dependencies

Rule: polynomial_evaluation_order · Uses: G001, S005

S007 · implies

Before

y′ at-1 ascending coefficients=[0]

After

evaluate at x=-1

Conditions: none

Evaluate ascending coefficients by Horner from the highest nonzero term down;ignoring redundant top zero terms changes neither the function nor the retained original list.

Step identifiers and dependencies

Rule: polynomial_evaluation_order · Uses: G001, S006

S008 · calculation

Before

p·y at-1 := mul(0, 5)

After

p·y at-1 = 0

Conditions: none

Compute the p-scaled function value on the right.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S007

S009 · calculation

Before

y′−p·y at-1 := sub(0, 0)

After

y′−p·y at-1 = 0

Conditions: none

Retain the correct subtraction order.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S008

S010 · calculation

Before

residual at-1 := sub(0, 0)

After

residual at-1 = 0

Conditions: none

Subtract q to obtain the full residual.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S009

S011 · implies

Before

residual at-1=0

After

point equation match=Yes

Conditions: none

This flag answers only for the current grid point.

Step identifiers and dependencies

Rule: point_equation_check · Uses: G001, S010

S012 · implies

Before

y at0 ascending coefficients=[5, 0]

After

evaluate at x=0

Conditions: none

Evaluate ascending coefficients by Horner from the highest nonzero term down;ignoring redundant top zero terms changes neither the function nor the retained original list.

Step identifiers and dependencies

Rule: polynomial_evaluation_order · Uses: G001, S011

S013 · implies

Before

y′ at0 ascending coefficients=[0]

After

evaluate at x=0

Conditions: none

Evaluate ascending coefficients by Horner from the highest nonzero term down;ignoring redundant top zero terms changes neither the function nor the retained original list.

Step identifiers and dependencies

Rule: polynomial_evaluation_order · Uses: G001, S012

S014 · calculation

Before

p·y at0 := mul(0, 5)

After

p·y at0 = 0

Conditions: none

Compute the p-scaled function value on the right.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S013

S015 · calculation

Before

y′−p·y at0 := sub(0, 0)

After

y′−p·y at0 = 0

Conditions: none

Retain the correct subtraction order.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S014

S016 · calculation

Before

residual at0 := sub(0, 0)

After

residual at0 = 0

Conditions: none

Subtract q to obtain the full residual.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S015

S017 · implies

Before

residual at0=0

After

point equation match=Yes

Conditions: none

This flag answers only for the current grid point.

Step identifiers and dependencies

Rule: point_equation_check · Uses: G001, S016

S018 · implies

Before

y at1 ascending coefficients=[5, 0]

After

evaluate at x=1

Conditions: none

Evaluate ascending coefficients by Horner from the highest nonzero term down;ignoring redundant top zero terms changes neither the function nor the retained original list.

Step identifiers and dependencies

Rule: polynomial_evaluation_order · Uses: G001, S017

S019 · implies

Before

y′ at1 ascending coefficients=[0]

After

evaluate at x=1

Conditions: none

Evaluate ascending coefficients by Horner from the highest nonzero term down;ignoring redundant top zero terms changes neither the function nor the retained original list.

Step identifiers and dependencies

Rule: polynomial_evaluation_order · Uses: G001, S018

S020 · calculation

Before

p·y at1 := mul(0, 5)

After

p·y at1 = 0

Conditions: none

Compute the p-scaled function value on the right.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S019

S021 · calculation

Before

y′−p·y at1 := sub(0, 0)

After

y′−p·y at1 = 0

Conditions: none

Retain the correct subtraction order.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S020

S022 · calculation

Before

residual at1 := sub(0, 0)

After

residual at1 = 0

Conditions: none

Subtract q to obtain the full residual.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S021

S023 · implies

Before

residual at1=0

After

point equation match=Yes

Conditions: none

This flag answers only for the current grid point.

Step identifiers and dependencies

Rule: point_equation_check · Uses: G001, S022

S024 · implies

Before

all listed grid points pass=Yes; initial conditions pass=Yes

After

combined finite check=Yes

Conditions: none

Every requested grid and initial condition must pass;do not omit a point or an initial condition.

Step identifiers and dependencies

Rule: finite_grid_initial_conjunction · Uses: G001, S023

S025 · implies

Before

finite grid agreement alone is not a general interval certificate

After

a polynomial coefficient/degree certificate is a separate possible strengthening

Conditions: none

For these polynomials,coefficient identity or a proved degree bound with enough distinct points could separately strengthen the evidence;this output flag records only the finite check,not a denial of that additional method.

Step identifiers and dependencies

Rule: grid_vs_interval_scope · Uses: G001, S024

Reverse checks

  • S025 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S024 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S023 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S022 · premise_and_result_audit — Recompute residual at1 with exact rational arithmetic, not rounded decimals.
  • S021 · premise_and_result_audit — Recompute y′−p·y at1 with exact rational arithmetic, not rounded decimals.
  • S020 · premise_and_result_audit — Recompute p·y at1 with exact rational arithmetic, not rounded decimals.
  • S019 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S018 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S017 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S016 · premise_and_result_audit — Recompute residual at0 with exact rational arithmetic, not rounded decimals.
  • S015 · premise_and_result_audit — Recompute y′−p·y at0 with exact rational arithmetic, not rounded decimals.
  • S014 · premise_and_result_audit — Recompute p·y at0 with exact rational arithmetic, not rounded decimals.
  • S013 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S012 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S011 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S010 · premise_and_result_audit — Recompute residual at-1 with exact rational arithmetic, not rounded decimals.
  • S009 · premise_and_result_audit — Recompute y′−p·y at-1 with exact rational arithmetic, not rounded decimals.
  • S008 · premise_and_result_audit — Recompute p·y at-1 with exact rational arithmetic, not rounded decimals.
  • 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 — Recompute y′ coefficient at degree0 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

([5, 0], 0, 0, [-1, 0, 1], [[-1, 5, 0, 0, Yes], [0, 5, 0, 0, Yes], [1, 5, 0, 0, Yes]], 0, 5, 5, Yes, 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: 328b5b91d9bb288b5ebda4e4364beada9d52a42786f53fe6dc211b079e1e7224
  • candidate record SHA-256: a3799964d289cf3db2cdd7a520d217edfb7297bb4af9ae3460b89281153d6a9b
  • semantic review receipt SHA-256: 5dbc70ebd5f74b23384c93b63a2b1d6519e206c79f22ae16a6c2d7483cea783f
  • question-first witness SHA-256: cf121c8dd2fec13aa118b04b049ee39494f1d6d9ecdc13514cafb78c0fc021fa
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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