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Question 27828: 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

R0054-27828 · q-20261015-pulse-20261119-r03-0028

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=[3, 4], linear b=[1, 0], and point x=[0, -1] 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=[3, 4], linear b=[1, 0], and point x=[0, -1] 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(3, 0)

After

GD ORIGINAL ORIGINAL gradient d*x coordinate0 = 0

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(0, 1)

After

GD ORIGINAL ORIGINAL gradient plus b coordinate0 = 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, S002

S004 · calculation

Before

GD ORIGINAL ORIGINAL gradient d*x coordinate1 := mul(4, -1)

After

GD ORIGINAL ORIGINAL gradient d*x 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, S003

S005 · calculation

Before

GD ORIGINAL ORIGINAL gradient plus b coordinate1 := sum(-4, 0)

After

GD ORIGINAL 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, S004

S006 · calculation

Before

GD ORIGINAL ORIGINAL objective SQUARE FIRST coordinate0 := mul(0, 0)

After

GD ORIGINAL ORIGINAL objective SQUARE FIRST coordinate0 = 0

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(3, 0)

After

GD ORIGINAL ORIGINAL diagonal times square coordinate0 = 0

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(0, 2)

After

GD ORIGINAL ORIGINAL quadratic divide2 coordinate0 = 0

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, 0)

After

GD ORIGINAL ORIGINAL linear product coordinate0 = 0

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(0, 0)

After

GD ORIGINAL ORIGINAL coordinate objective sum0 = 0

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, 0)

After

GD ORIGINAL ORIGINAL objective running sum0 = 0

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(-1, -1)

After

GD ORIGINAL 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, S011

S013 · calculation

Before

GD ORIGINAL ORIGINAL diagonal times square coordinate1 := mul(4, 1)

After

GD ORIGINAL ORIGINAL diagonal times square 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, S012

S014 · calculation

Before

GD ORIGINAL ORIGINAL quadratic divide2 coordinate1 := div(4, 2)

After

GD ORIGINAL ORIGINAL quadratic divide2 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, S013

S015 · calculation

Before

GD ORIGINAL ORIGINAL linear product coordinate1 := mul(0, -1)

After

GD ORIGINAL ORIGINAL linear product coordinate1 = 0

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(2, 0)

After

GD ORIGINAL ORIGINAL coordinate objective sum1 = 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, S015

S017 · calculation

Before

GD ORIGINAL ORIGINAL objective running sum1 := sum(0, 2)

After

GD ORIGINAL ORIGINAL objective running sum1 = 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, S016

S018 · implies

Before

source roles = [GD ORIGINAL, [3, 4], [1, 0], [0, -1]]

After

derived = [[3, 4], [1, 0], [0, -1], [1, -4], 2]

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, 1)

After

GD ORIGINAL one step ORIGINAL alpha times gradient0 = 1/4

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(0, 1/4)

After

GD ORIGINAL one step ORIGINAL next coordinate0 = -1/4

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, -4)

After

GD ORIGINAL one step ORIGINAL alpha times gradient1 = -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, S020

S022 · calculation

Before

GD ORIGINAL one step ORIGINAL next coordinate1 := sub(-1, -1)

After

GD ORIGINAL one step ORIGINAL next coordinate1 = 0

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(3, -1/4)

After

GD ORIGINAL one step next recomputation ORIGINAL gradient d*x coordinate0 = -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, S022

S024 · calculation

Before

GD ORIGINAL one step next recomputation ORIGINAL gradient plus b coordinate0 := sum(-3/4, 1)

After

GD ORIGINAL one step next recomputation ORIGINAL gradient plus b coordinate0 = 1/4

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(4, 0)

After

GD ORIGINAL one step next recomputation ORIGINAL gradient d*x coordinate1 = 0

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(0, 0)

After

GD ORIGINAL one step next recomputation ORIGINAL gradient plus b coordinate1 = 0

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(-1/4, -1/4)

After

GD ORIGINAL one step next recomputation ORIGINAL objective SQUARE FIRST coordinate0 = 1/16

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(3, 1/16)

After

GD ORIGINAL one step next recomputation ORIGINAL diagonal times square coordinate0 = 3/16

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(3/16, 2)

After

GD ORIGINAL one step next recomputation ORIGINAL quadratic divide2 coordinate0 = 3/32

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, -1/4)

After

GD ORIGINAL one step next recomputation ORIGINAL linear product coordinate0 = -1/4

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(3/32, -1/4)

After

GD ORIGINAL one step next recomputation ORIGINAL coordinate objective sum0 = -5/32

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, -5/32)

After

GD ORIGINAL one step next recomputation ORIGINAL objective running sum0 = -5/32

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(0, 0)

After

GD ORIGINAL one step next recomputation ORIGINAL objective SQUARE FIRST coordinate1 = 0

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(4, 0)

After

GD ORIGINAL one step next recomputation ORIGINAL diagonal times square coordinate1 = 0

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(0, 2)

After

GD ORIGINAL one step next recomputation ORIGINAL quadratic divide2 coordinate1 = 0

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(0, 0)

After

GD ORIGINAL one step next recomputation ORIGINAL linear product coordinate1 = 0

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(0, 0)

After

GD ORIGINAL one step next recomputation ORIGINAL coordinate objective sum1 = 0

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(-5/32, 0)

After

GD ORIGINAL one step next recomputation ORIGINAL objective running sum1 = -5/32

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, [[3, 1], [4, 1]], [[1, 1], [0, 1]], [[-1, 4], [0, 1]]]

After

derived = [[3, 4], [1, 0], [-1/4, 0], [1/4, 0], -5/32]

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 = [[0, -1], [1, -4], 1/4]

After

derived = [[-1/4, 0], 2, -5/32, 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

([0, -1], [1, -4], 1/4, [-1/4, 0], 2, -5/32, 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: 16b5d0e5a10483eb71781bebb7845197c11dfaea27b6e1c1de84ace8781b7f2e
  • candidate record SHA-256: 0d06eb48152720fd65e9d8287ed8c8d08a2c5583d1acefea5c33669a70fbe253
  • semantic review receipt SHA-256: 0a76d8e93c08bb16998a0483f3dfc0504f269fc3e1982e6cd868cab0a2856d54
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  • Lean: NOT_RUN · human review: NOT_PERFORMED
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