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Question 27826: Positive Step Size Alone Does Not Guarantee Objective Descent

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

R0054-27826 · q-20261015-pulse-20261119-r03-0026

Original question and givens

Use f(x)=1/2*sum_i d_i*x_i^2+sum_i b_i*x_i, with positive diagonal d=[1, 2], linear b=[-1, -2], and point x=[-2, -3] in fixed standard Euclidean coordinates. Use positive step size alpha=1/4. Give (point, gradient, step_size, next_point, objective_before, objective_after, nonincreasing, step_scope).

  • G001 — Use f(x)=1/2*sum_i d_i*x_i^2+sum_i b_i*x_i, with positive diagonal d=[1, 2], linear b=[-1, -2], and point x=[-2, -3] in fixed standard Euclidean coordinates. Use positive step size alpha=1/4. Give (point, gradient, step_size, next_point, objective_before, objective_after, nonincreasing, step_scope).

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

source roles = [gd-one-step]

After

derived = [[point, gradient, step_size, next_point, objective_before, objective_after, nonincreasing, step_scope]]

Conditions: none

List the complete operation/mode field order without JavaScript or answer-shape inference;Boolean,string,null and an unclaimed result remain distinct.

Step identifiers and dependencies

Rule: source_ordered_fields_without_JS · Uses: G001

S002 · calculation

Before

GD ORIGINAL ORIGINAL gradient d*x coordinate0 := mul(1, -2)

After

GD ORIGINAL ORIGINAL gradient d*x coordinate0 = -2

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S001

S003 · calculation

Before

GD ORIGINAL ORIGINAL gradient plus b coordinate0 := sum(-2, -1)

After

GD ORIGINAL ORIGINAL gradient plus b coordinate0 = -3

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S002

S004 · calculation

Before

GD ORIGINAL ORIGINAL gradient d*x coordinate1 := mul(2, -3)

After

GD ORIGINAL ORIGINAL gradient d*x coordinate1 = -6

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S003

S005 · calculation

Before

GD ORIGINAL ORIGINAL gradient plus b coordinate1 := sum(-6, -2)

After

GD ORIGINAL ORIGINAL gradient plus b coordinate1 = -8

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S004

S006 · calculation

Before

GD ORIGINAL ORIGINAL objective SQUARE FIRST coordinate0 := mul(-2, -2)

After

GD ORIGINAL ORIGINAL objective SQUARE FIRST coordinate0 = 4

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S005

S007 · calculation

Before

GD ORIGINAL ORIGINAL diagonal times square coordinate0 := mul(1, 4)

After

GD ORIGINAL ORIGINAL diagonal times square coordinate0 = 4

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S006

S008 · calculation

Before

GD ORIGINAL ORIGINAL quadratic divide2 coordinate0 := div(4, 2)

After

GD ORIGINAL ORIGINAL quadratic divide2 coordinate0 = 2

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S007

S009 · calculation

Before

GD ORIGINAL ORIGINAL linear product coordinate0 := mul(-1, -2)

After

GD ORIGINAL ORIGINAL linear product coordinate0 = 2

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S008

S010 · calculation

Before

GD ORIGINAL ORIGINAL coordinate objective sum0 := sum(2, 2)

After

GD ORIGINAL ORIGINAL coordinate objective sum0 = 4

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S009

S011 · calculation

Before

GD ORIGINAL ORIGINAL objective running sum0 := sum(0, 4)

After

GD ORIGINAL ORIGINAL objective running sum0 = 4

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S010

S012 · calculation

Before

GD ORIGINAL ORIGINAL objective SQUARE FIRST coordinate1 := mul(-3, -3)

After

GD ORIGINAL ORIGINAL objective SQUARE FIRST coordinate1 = 9

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S011

S013 · calculation

Before

GD ORIGINAL ORIGINAL diagonal times square coordinate1 := mul(2, 9)

After

GD ORIGINAL ORIGINAL diagonal times square coordinate1 = 18

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S012

S014 · calculation

Before

GD ORIGINAL ORIGINAL quadratic divide2 coordinate1 := div(18, 2)

After

GD ORIGINAL ORIGINAL quadratic divide2 coordinate1 = 9

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S013

S015 · calculation

Before

GD ORIGINAL ORIGINAL linear product coordinate1 := mul(-2, -3)

After

GD ORIGINAL ORIGINAL linear product coordinate1 = 6

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S014

S016 · calculation

Before

GD ORIGINAL ORIGINAL coordinate objective sum1 := sum(9, 6)

After

GD ORIGINAL ORIGINAL coordinate objective sum1 = 15

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S015

S017 · calculation

Before

GD ORIGINAL ORIGINAL objective running sum1 := sum(4, 15)

After

GD ORIGINAL ORIGINAL objective running sum1 = 19

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S016

S018 · implies

Before

source roles = [GD ORIGINAL, [1, 2], [-1, -2], [-2, -3]]

After

derived = [[1, 2], [-1, -2], [-2, -3], [-3, -8], 19]

Conditions: none

For the WHOLE specified f(x)=1/2 sum d_i x_i²+sum b_i x_i,differentiate each coordinate to d_i x_i+b_i,not2d_i x_i.Compute ALL gradient entries first,then the objective in original order,squaring before multiplying d_i.Qualify positive diagonals,dimensions and coordinate order.

Step identifiers and dependencies

Rule: GD_WHOLE_positive_diagonal_quadratic_ordered_gradient_and_objective · Uses: G001, S017

S019 · calculation

Before

GD ORIGINAL one step ORIGINAL alpha times gradient0 := mul(1/4, -3)

After

GD ORIGINAL one step ORIGINAL alpha times gradient0 = -3/4

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S018

S020 · calculation

Before

GD ORIGINAL one step ORIGINAL next coordinate0 := sub(-2, -3/4)

After

GD ORIGINAL one step ORIGINAL next coordinate0 = -5/4

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S019

S021 · calculation

Before

GD ORIGINAL one step ORIGINAL alpha times gradient1 := mul(1/4, -8)

After

GD ORIGINAL one step ORIGINAL alpha times gradient1 = -2

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S020

S022 · calculation

Before

GD ORIGINAL one step ORIGINAL next coordinate1 := sub(-3, -2)

After

GD ORIGINAL one step ORIGINAL next coordinate1 = -1

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S021

S023 · calculation

Before

GD ORIGINAL one step next recomputation ORIGINAL gradient d*x coordinate0 := mul(1, -5/4)

After

GD ORIGINAL one step next recomputation ORIGINAL gradient d*x coordinate0 = -5/4

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S022

S024 · calculation

Before

GD ORIGINAL one step next recomputation ORIGINAL gradient plus b coordinate0 := sum(-5/4, -1)

After

GD ORIGINAL one step next recomputation ORIGINAL gradient plus b coordinate0 = -9/4

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S023

S025 · calculation

Before

GD ORIGINAL one step next recomputation ORIGINAL gradient d*x coordinate1 := mul(2, -1)

After

GD ORIGINAL one step next recomputation ORIGINAL gradient d*x coordinate1 = -2

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S024

S026 · calculation

Before

GD ORIGINAL one step next recomputation ORIGINAL gradient plus b coordinate1 := sum(-2, -2)

After

GD ORIGINAL one step next recomputation ORIGINAL gradient plus b coordinate1 = -4

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S025

S027 · calculation

Before

GD ORIGINAL one step next recomputation ORIGINAL objective SQUARE FIRST coordinate0 := mul(-5/4, -5/4)

After

GD ORIGINAL one step next recomputation ORIGINAL objective SQUARE FIRST coordinate0 = 25/16

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S026

S028 · calculation

Before

GD ORIGINAL one step next recomputation ORIGINAL diagonal times square coordinate0 := mul(1, 25/16)

After

GD ORIGINAL one step next recomputation ORIGINAL diagonal times square coordinate0 = 25/16

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S027

S029 · calculation

Before

GD ORIGINAL one step next recomputation ORIGINAL quadratic divide2 coordinate0 := div(25/16, 2)

After

GD ORIGINAL one step next recomputation ORIGINAL quadratic divide2 coordinate0 = 25/32

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S028

S030 · calculation

Before

GD ORIGINAL one step next recomputation ORIGINAL linear product coordinate0 := mul(-1, -5/4)

After

GD ORIGINAL one step next recomputation ORIGINAL linear product coordinate0 = 5/4

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S029

S031 · calculation

Before

GD ORIGINAL one step next recomputation ORIGINAL coordinate objective sum0 := sum(25/32, 5/4)

After

GD ORIGINAL one step next recomputation ORIGINAL coordinate objective sum0 = 65/32

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S030

S032 · calculation

Before

GD ORIGINAL one step next recomputation ORIGINAL objective running sum0 := sum(0, 65/32)

After

GD ORIGINAL one step next recomputation ORIGINAL objective running sum0 = 65/32

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S031

S033 · calculation

Before

GD ORIGINAL one step next recomputation ORIGINAL objective SQUARE FIRST coordinate1 := mul(-1, -1)

After

GD ORIGINAL one step next recomputation ORIGINAL objective SQUARE FIRST coordinate1 = 1

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S032

S034 · calculation

Before

GD ORIGINAL one step next recomputation ORIGINAL diagonal times square coordinate1 := mul(2, 1)

After

GD ORIGINAL one step next recomputation ORIGINAL diagonal times square coordinate1 = 2

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S033

S035 · calculation

Before

GD ORIGINAL one step next recomputation ORIGINAL quadratic divide2 coordinate1 := div(2, 2)

After

GD ORIGINAL one step next recomputation ORIGINAL quadratic divide2 coordinate1 = 1

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S034

S036 · calculation

Before

GD ORIGINAL one step next recomputation ORIGINAL linear product coordinate1 := mul(-2, -1)

After

GD ORIGINAL one step next recomputation ORIGINAL linear product coordinate1 = 2

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S035

S037 · calculation

Before

GD ORIGINAL one step next recomputation ORIGINAL coordinate objective sum1 := sum(1, 2)

After

GD ORIGINAL one step next recomputation ORIGINAL coordinate objective sum1 = 3

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S036

S038 · calculation

Before

GD ORIGINAL one step next recomputation ORIGINAL objective running sum1 := sum(65/32, 3)

After

GD ORIGINAL one step next recomputation ORIGINAL objective running sum1 = 161/32

Conditions: none

Substitute original roles and established intermediates exactly,not approximations or internally consistent changed operands;extra teaching algebra adds no source-domain gate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S037

S039 · implies

Before

source roles = [GD ORIGINAL one step next recomputation, [[1, 1], [2, 1]], [[-1, 1], [-2, 1]], [[-5, 4], [-1, 1]]]

After

derived = [[1, 2], [-1, -2], [-5/4, -1], [-9/4, -4], 161/32]

Conditions: none

For the WHOLE specified f(x)=1/2 sum d_i x_i²+sum b_i x_i,differentiate each coordinate to d_i x_i+b_i,not2d_i x_i.Compute ALL gradient entries first,then the objective in original order,squaring before multiplying d_i.Qualify positive diagonals,dimensions and coordinate order.

Step identifiers and dependencies

Rule: GD_WHOLE_positive_diagonal_quadratic_ordered_gradient_and_objective · Uses: G001, S038

S040 · implies

Before

source roles = [[-2, -3], [-3, -8], 1/4]

After

derived = [[-5/4, -1], 19, 161/32, Yes]

Conditions: none

This family requires only a positive step and compares the ACTUAL objectives.The flag can be False.A positive_step description does not imply descent,and no stronger safe-step guard is added.

Step identifiers and dependencies

Rule: GD_one_positive_step_ACTUAL_objective_comparison_not_safe_assumption · Uses: G001, S039

Reverse checks

  • S040 · premise_and_result_audit — Reverse-check original data,operands,complete scope and premises;finite witnesses,conditional theorem use and formal proof remain distinct.
  • S039 · premise_and_result_audit — Reverse-check original data,operands,complete scope and premises;finite witnesses,conditional theorem use and formal proof remain distinct.
  • S038 · premise_and_result_audit — Recompute GD ORIGINAL one step next recomputation ORIGINAL objective running sum1 with exact rational arithmetic, not rounded decimals.
  • S037 · premise_and_result_audit — Recompute GD ORIGINAL one step next recomputation ORIGINAL coordinate objective sum1 with exact rational arithmetic, not rounded decimals.
  • S036 · premise_and_result_audit — Recompute GD ORIGINAL one step next recomputation ORIGINAL linear product coordinate1 with exact rational arithmetic, not rounded decimals.
  • S035 · premise_and_result_audit — Recompute GD ORIGINAL one step next recomputation ORIGINAL quadratic divide2 coordinate1 with exact rational arithmetic, not rounded decimals.
  • S034 · premise_and_result_audit — Recompute GD ORIGINAL one step next recomputation ORIGINAL diagonal times square coordinate1 with exact rational arithmetic, not rounded decimals.
  • S033 · premise_and_result_audit — Recompute GD ORIGINAL one step next recomputation ORIGINAL objective SQUARE FIRST coordinate1 with exact rational arithmetic, not rounded decimals.
  • S032 · premise_and_result_audit — Recompute GD ORIGINAL one step next recomputation ORIGINAL objective running sum0 with exact rational arithmetic, not rounded decimals.
  • S031 · premise_and_result_audit — Recompute GD ORIGINAL one step next recomputation ORIGINAL coordinate objective sum0 with exact rational arithmetic, not rounded decimals.
  • S030 · premise_and_result_audit — Recompute GD ORIGINAL one step next recomputation ORIGINAL linear product coordinate0 with exact rational arithmetic, not rounded decimals.
  • S029 · premise_and_result_audit — Recompute GD ORIGINAL one step next recomputation ORIGINAL quadratic divide2 coordinate0 with exact rational arithmetic, not rounded decimals.
  • S028 · premise_and_result_audit — Recompute GD ORIGINAL one step next recomputation ORIGINAL diagonal times square coordinate0 with exact rational arithmetic, not rounded decimals.
  • S027 · premise_and_result_audit — Recompute GD ORIGINAL one step next recomputation ORIGINAL objective SQUARE FIRST coordinate0 with exact rational arithmetic, not rounded decimals.
  • S026 · premise_and_result_audit — Recompute GD ORIGINAL one step next recomputation ORIGINAL gradient plus b coordinate1 with exact rational arithmetic, not rounded decimals.
  • S025 · premise_and_result_audit — Recompute GD ORIGINAL one step next recomputation ORIGINAL gradient d*x coordinate1 with exact rational arithmetic, not rounded decimals.
  • S024 · premise_and_result_audit — Recompute GD ORIGINAL one step next recomputation ORIGINAL gradient plus b coordinate0 with exact rational arithmetic, not rounded decimals.
  • S023 · premise_and_result_audit — Recompute GD ORIGINAL one step next recomputation ORIGINAL gradient d*x coordinate0 with exact rational arithmetic, not rounded decimals.
  • S022 · premise_and_result_audit — Recompute GD ORIGINAL one step ORIGINAL next coordinate1 with exact rational arithmetic, not rounded decimals.
  • S021 · premise_and_result_audit — Recompute GD ORIGINAL one step ORIGINAL alpha times gradient1 with exact rational arithmetic, not rounded decimals.
  • S020 · premise_and_result_audit — Recompute GD ORIGINAL one step ORIGINAL next coordinate0 with exact rational arithmetic, not rounded decimals.
  • S019 · premise_and_result_audit — Recompute GD ORIGINAL one step ORIGINAL alpha times gradient0 with exact rational arithmetic, not rounded decimals.
  • S018 · premise_and_result_audit — Reverse-check original data,operands,complete scope and premises;finite witnesses,conditional theorem use and formal proof remain distinct.
  • S017 · premise_and_result_audit — Recompute GD ORIGINAL ORIGINAL objective running sum1 with exact rational arithmetic, not rounded decimals.
  • S016 · premise_and_result_audit — Recompute GD ORIGINAL ORIGINAL coordinate objective sum1 with exact rational arithmetic, not rounded decimals.
  • S015 · premise_and_result_audit — Recompute GD ORIGINAL ORIGINAL linear product coordinate1 with exact rational arithmetic, not rounded decimals.
  • S014 · premise_and_result_audit — Recompute GD ORIGINAL ORIGINAL quadratic divide2 coordinate1 with exact rational arithmetic, not rounded decimals.
  • S013 · premise_and_result_audit — Recompute GD ORIGINAL ORIGINAL diagonal times square coordinate1 with exact rational arithmetic, not rounded decimals.
  • S012 · premise_and_result_audit — Recompute GD ORIGINAL ORIGINAL objective SQUARE FIRST coordinate1 with exact rational arithmetic, not rounded decimals.
  • S011 · premise_and_result_audit — Recompute GD ORIGINAL ORIGINAL objective running sum0 with exact rational arithmetic, not rounded decimals.
  • S010 · premise_and_result_audit — Recompute GD ORIGINAL ORIGINAL coordinate objective sum0 with exact rational arithmetic, not rounded decimals.
  • S009 · premise_and_result_audit — Recompute GD ORIGINAL ORIGINAL linear product coordinate0 with exact rational arithmetic, not rounded decimals.
  • S008 · premise_and_result_audit — Recompute GD ORIGINAL ORIGINAL quadratic divide2 coordinate0 with exact rational arithmetic, not rounded decimals.
  • S007 · premise_and_result_audit — Recompute GD ORIGINAL ORIGINAL diagonal times square coordinate0 with exact rational arithmetic, not rounded decimals.
  • S006 · premise_and_result_audit — Recompute GD ORIGINAL ORIGINAL objective SQUARE FIRST coordinate0 with exact rational arithmetic, not rounded decimals.
  • S005 · premise_and_result_audit — Recompute GD ORIGINAL ORIGINAL gradient plus b coordinate1 with exact rational arithmetic, not rounded decimals.
  • S004 · premise_and_result_audit — Recompute GD ORIGINAL ORIGINAL gradient d*x coordinate1 with exact rational arithmetic, not rounded decimals.
  • S003 · premise_and_result_audit — Recompute GD ORIGINAL ORIGINAL gradient plus b coordinate0 with exact rational arithmetic, not rounded decimals.
  • S002 · premise_and_result_audit — Recompute GD ORIGINAL ORIGINAL gradient d*x coordinate0 with exact rational arithmetic, not rounded decimals.
  • S001 · premise_and_result_audit — Reverse-check original data,operands,complete scope and premises;finite witnesses,conditional theorem use and formal proof remain distinct.

Result

([-2, -3], [-3, -8], 1/4, [-5/4, -1], 19, 161/32, Yes, positive_step_alone_does_not_guarantee_descent)

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: 583202c7ec9e04ca8f9264f579d875eb565f46b4c27f499d0809000f012d4987
  • candidate record SHA-256: 18a444918e047b64878d4980a05a9223a7ef33439324c9bd81ec57b916065f42
  • semantic review receipt SHA-256: 0a76d8e93c08bb16998a0483f3dfc0504f269fc3e1982e6cd868cab0a2856d54
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  • Lean: NOT_RUN · human review: NOT_PERFORMED
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