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Question 21959: A Cell-Constant Conditional Version Has the Same Expectation

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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R0042-21959 · q-20261014-advance-20261109-r04-law-of-total-expectation-0059

Original question and givens

Use the complete normalized finite law masses=[1/18, 2/18, 15/18, 0/1], aligned values X=[8, 9, 11, 107] and complete disjoint partition=[[0, 1], [2, 3]] covering every atom. Values are integrable in this finite model. Cell order and atom order are retained; independence is not required. Conditional quotients require strictly positive cell mass. Give (conditional_values, tower_expectation, mean, equal, certificate).

  • G001 — Use the complete normalized finite law masses=[1/18, 2/18, 15/18, 0/1], aligned values X=[8, 9, 11, 107] and complete disjoint partition=[[0, 1], [2, 3]] covering every atom. Values are integrable in this finite model. Cell order and atom order are retained; independence is not required. Conditional quotients require strictly positive cell mass. Give (conditional_values, tower_expectation, mean, equal, certificate).

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 operation=totalexp-tower-identity;original snapshot and mathematics retained

After

explicit ordered source output fields=[conditional_values, tower_expectation, mean, equal, certificate]

Conditions: none

Keep the original historical interface marker while listing ordered source fields without JavaScript.Tags are not additional evidence;fixed No markers retain their source claim scope.

Step identifiers and dependencies

Rule: source_ordered_interface_explicit_without_javascript · Uses: G001

S002 · calculation

Before

Total expectation complete original mass := sum(1/18, 1/9, 5/6, 0)

After

Total expectation complete original mass = 1

Conditions: none

Substitute the original roles,order and conditions term by term with exact arithmetic,not floating-point approximation.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S001

S003 · calculation

Before

Total expectation original atom0 weighted X := mul(1/18, 8)

After

Total expectation original atom0 weighted X = 4/9

Conditions: none

Substitute the original roles,order and conditions term by term with exact arithmetic,not floating-point approximation.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S002

S004 · calculation

Before

Total expectation original atom1 weighted X := mul(1/9, 9)

After

Total expectation original atom1 weighted X = 1

Conditions: none

Substitute the original roles,order and conditions term by term with exact arithmetic,not floating-point approximation.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S003

S005 · calculation

Before

Total expectation original atom2 weighted X := mul(5/6, 11)

After

Total expectation original atom2 weighted X = 55/6

Conditions: none

Substitute the original roles,order and conditions term by term with exact arithmetic,not floating-point approximation.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S004

S006 · calculation

Before

Total expectation original atom3 weighted X := mul(0, 107)

After

Total expectation original atom3 weighted X = 0

Conditions: none

Substitute the original roles,order and conditions term by term with exact arithmetic,not floating-point approximation.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S005

S007 · calculation

Before

Total expectation full original mean := sum(4/9, 1, 55/6, 0)

After

Total expectation full original mean = 191/18

Conditions: none

Substitute the original roles,order and conditions term by term with exact arithmetic,not floating-point approximation.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S006

S008 · implies

Before

ORIGINAL masses=[1/18, 1/9, 5/6, 0],SIGNED values X=[8, 9, 11, 107];ORIGINAL cell order=[[0, 1], [2, 3]]

After

flattened original atom labels=[0, 1, 2, 3] cover EVERY atom exactly ONCE including null atoms;total mass=1;integrable finite mean=191/18;NO independence premise

Conditions: none

The partition covers all original atoms,including null atoms,exactly once.Keep original cell order and source-normalized internal labels.X may be signed and is integrable in this finite model;independence is not required.

Step identifiers and dependencies

Rule: totalexp_same_law_complete_disjoint_partition_all_atoms · Uses: G001, S007

S009 · calculation

Before

Total expectation cell0 mass := sum(1/18, 1/9)

After

Total expectation cell0 mass = 1/6

Conditions: none

Substitute the original roles,order and conditions term by term with exact arithmetic,not floating-point approximation.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S008

S010 · calculation

Before

Total expectation cell0 numerator := sum(4/9, 1)

After

Total expectation cell0 numerator = 13/9

Conditions: none

Substitute the original roles,order and conditions term by term with exact arithmetic,not floating-point approximation.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S009

S011 · calculation

Before

Total expectation cell0 positive-mass conditional mean := div(13/9, 1/6)

After

Total expectation cell0 positive-mass conditional mean = 26/3

Conditions: none

Substitute the original roles,order and conditions term by term with exact arithmetic,not floating-point approximation.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S010

S012 · implies

Before

ORIGINAL cell index=0,atom labels=[0, 1];mass=1/6;weighted numerator=13/9

After

conditional quotient=26/3;positive denominator qualifies division

Conditions: none

Divide only for positive cell mass.In a null cell,all nonnegative atom masses are0,so the numerator is0 but0/0 remains undefined.Keep null rather than an asserted quotient0,including empty cells.

Step identifiers and dependencies

Rule: totalexp_cell_quotient_positive_mass_only_null_preserved · Uses: G001, S011

S013 · calculation

Before

Total expectation cell1 mass := sum(5/6, 0)

After

Total expectation cell1 mass = 5/6

Conditions: none

Substitute the original roles,order and conditions term by term with exact arithmetic,not floating-point approximation.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S012

S014 · calculation

Before

Total expectation cell1 numerator := sum(55/6, 0)

After

Total expectation cell1 numerator = 55/6

Conditions: none

Substitute the original roles,order and conditions term by term with exact arithmetic,not floating-point approximation.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S013

S015 · calculation

Before

Total expectation cell1 positive-mass conditional mean := div(55/6, 5/6)

After

Total expectation cell1 positive-mass conditional mean = 11

Conditions: none

Substitute the original roles,order and conditions term by term with exact arithmetic,not floating-point approximation.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S014

S016 · implies

Before

ORIGINAL cell index=1,atom labels=[2, 3];mass=5/6;weighted numerator=55/6

After

conditional quotient=11;positive denominator qualifies division

Conditions: none

Divide only for positive cell mass.In a null cell,all nonnegative atom masses are0,so the numerator is0 but0/0 remains undefined.Keep null rather than an asserted quotient0,including empty cells.

Step identifiers and dependencies

Rule: totalexp_cell_quotient_positive_mass_only_null_preserved · Uses: G001, S015

S017 · calculation

Before

Total expectation positive cell0 weighted mean := mul(1/6, 26/3)

After

Total expectation positive cell0 weighted mean = 13/9

Conditions: none

Substitute the original roles,order and conditions term by term with exact arithmetic,not floating-point approximation.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S016

S018 · calculation

Before

Total expectation positive cell1 weighted mean := mul(5/6, 11)

After

Total expectation positive cell1 weighted mean = 55/6

Conditions: none

Substitute the original roles,order and conditions term by term with exact arithmetic,not floating-point approximation.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S017

S019 · calculation

Before

Total expectation sum positive-cell weighted means := sum(13/9, 55/6)

After

Total expectation sum positive-cell weighted means = 191/18

Conditions: none

Substitute the original roles,order and conditions term by term with exact arithmetic,not floating-point approximation.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S018

S020 · implies

Before

ALL original cell rows[index,atoms,mass,conditional_or_null,numerator]=[[0, [0, 1], 1/6, 26/3, 13/9], [1, [2, 3], 5/6, 11, 55/6]]

After

positive-cell weighted sum=191/18;ORIGINAL global mean=191/18;equal=Yes;disjoint complete cells regroup EVERY original p_i*X_i exactly ONCE,null contributions0

Conditions: none

Each positive mass times its conditional mean recovers its numerator;null cells contribute0.Disjoint complete cells then regroup every original weighted term exactly once.This proves the finite identity,not an unweighted average or an accidental numerical equality.

Step identifiers and dependencies

Rule: totalexp_regroup_complete_partition_general_identity · Uses: G001, S019

S021 · calculation

Before

Total expectation tower atom0 weighted conditional version := mul(1/18, 26/3)

After

Total expectation tower atom0 weighted conditional version = 13/27

Conditions: none

Substitute the original roles,order and conditions term by term with exact arithmetic,not floating-point approximation.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S020

S022 · calculation

Before

Total expectation tower atom1 weighted conditional version := mul(1/9, 26/3)

After

Total expectation tower atom1 weighted conditional version = 26/27

Conditions: none

Substitute the original roles,order and conditions term by term with exact arithmetic,not floating-point approximation.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S021

S023 · calculation

Before

Total expectation tower atom2 weighted conditional version := mul(5/6, 11)

After

Total expectation tower atom2 weighted conditional version = 55/6

Conditions: none

Substitute the original roles,order and conditions term by term with exact arithmetic,not floating-point approximation.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S022

S024 · calculation

Before

Total expectation tower atom3 weighted conditional version := mul(0, 11)

After

Total expectation tower atom3 weighted conditional version = 0

Conditions: none

Substitute the original roles,order and conditions term by term with exact arithmetic,not floating-point approximation.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S023

S025 · calculation

Before

Total expectation full tower expectation := sum(13/27, 26/27, 55/6, 0)

After

Total expectation full tower expectation = 191/18

Conditions: none

Substitute the original roles,order and conditions term by term with exact arithmetic,not floating-point approximation.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S024

S026 · implies

Before

ORIGINAL atom-order conditional version=[26/3, 26/3, 11, 11];ORIGINAL cells=[[0, 1], [2, 3]]

After

version constant on each cell,so measurable for sigma(partition);each cell integral equals original X cell integral;null-cell version CHOSEN0,not quotient;E(E(X|G))=191/18=E(X)=191/18

Conditions: none

Cell-constant values are measurable for the sigma-algebra generated by the partition.Cellwise integral identities extend to its finite cell unions,establishing a conditional-expectation version.On null cells0 is chosen,not a unique quotient.Weight by the original atom masses to obtain the tower identity.

Step identifiers and dependencies

Rule: totalexp_conditional_version_cell_measurability_and_tower · Uses: G001, S025

Reverse checks

  • S026 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S025 · premise_and_result_audit — Recompute Total expectation full tower expectation with exact rational arithmetic, not rounded decimals.
  • S024 · premise_and_result_audit — Recompute Total expectation tower atom3 weighted conditional version with exact rational arithmetic, not rounded decimals.
  • S023 · premise_and_result_audit — Recompute Total expectation tower atom2 weighted conditional version with exact rational arithmetic, not rounded decimals.
  • S022 · premise_and_result_audit — Recompute Total expectation tower atom1 weighted conditional version with exact rational arithmetic, not rounded decimals.
  • S021 · premise_and_result_audit — Recompute Total expectation tower atom0 weighted conditional version with exact rational arithmetic, not rounded decimals.
  • S020 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S019 · premise_and_result_audit — Recompute Total expectation sum positive-cell weighted means with exact rational arithmetic, not rounded decimals.
  • S018 · premise_and_result_audit — Recompute Total expectation positive cell1 weighted mean with exact rational arithmetic, not rounded decimals.
  • S017 · premise_and_result_audit — Recompute Total expectation positive cell0 weighted mean with exact rational arithmetic, not rounded decimals.
  • S016 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S015 · premise_and_result_audit — Recompute Total expectation cell1 positive-mass conditional mean with exact rational arithmetic, not rounded decimals.
  • S014 · premise_and_result_audit — Recompute Total expectation cell1 numerator with exact rational arithmetic, not rounded decimals.
  • S013 · premise_and_result_audit — Recompute Total expectation cell1 mass with exact rational arithmetic, not rounded decimals.
  • 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 — Recompute Total expectation cell0 positive-mass conditional mean with exact rational arithmetic, not rounded decimals.
  • S010 · premise_and_result_audit — Recompute Total expectation cell0 numerator with exact rational arithmetic, not rounded decimals.
  • S009 · premise_and_result_audit — Recompute Total expectation cell0 mass with exact rational arithmetic, not rounded decimals.
  • S008 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S007 · premise_and_result_audit — Recompute Total expectation full original mean with exact rational arithmetic, not rounded decimals.
  • S006 · premise_and_result_audit — Recompute Total expectation original atom3 weighted X with exact rational arithmetic, not rounded decimals.
  • S005 · premise_and_result_audit — Recompute Total expectation original atom2 weighted X with exact rational arithmetic, not rounded decimals.
  • S004 · premise_and_result_audit — Recompute Total expectation original atom1 weighted X with exact rational arithmetic, not rounded decimals.
  • S003 · premise_and_result_audit — Recompute Total expectation original atom0 weighted X with exact rational arithmetic, not rounded decimals.
  • S002 · premise_and_result_audit — Recompute Total expectation complete original mass 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

([26/3, 26/3, 11, 11], 191/18, 191/18, Yes, conditional_expectation_constant_on_partition_cells)

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: 2954984cde5de91905dc89241ab3866ef35563cb3ddc2d2c099a6f9add568dc6
  • candidate record SHA-256: 3f40f4dd72ff6a9a2b21f28ace8974f96d10cd39dacebd7a1bc93d12cbb788db
  • semantic review receipt SHA-256: dd44555041dfbb6fe9936aa00b9a5f8c5982c2784ef61dd0cbd5d1a303a49c1a
  • question-first witness SHA-256: 9a6011263f6ac53b9a1fd57addf2f3e2f6088b54802c539f332d689480dc2d17
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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