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Question 14198: Total Expectation Is a Consequence, Not the Whole Definition

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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R0027-14198 · q-20261014-advance-20261029-r04-conditional-expectation-0098

Original question and givens

Use one complete finite probability space with outcome indices 0 through 3, aligned masses=[8/49, 20/49, 6/49, 15/49], values X=[10, -2, 24, -10], and conditioning-block labels=[0, 1, 1, 2]. Masses are nonnegative and total exactly 1. Block labels describe a partition of this same space; list block summaries in increasing label order and outcomes in original index order. Conditional expectation is constant on each positive-mass block, with its weighted mean, and preserves every block integral. A zero-mass block is only determined almost surely: return a.s._arbitrary, never divide by zero. Use exact reduced fractions with positive denominators, omitting /1 for integers. Give (E_X,E_conditional,equal?,tower_to_trivial_sigma_algebra).

  • G001 — Use one complete finite probability space with outcome indices 0 through 3, aligned masses=[8/49, 20/49, 6/49, 15/49], values X=[10, -2, 24, -10], and conditioning-block labels=[0, 1, 1, 2]. Masses are nonnegative and total exactly 1. Block labels describe a partition of this same space; list block summaries in increasing label order and outcomes in original index order. Conditional expectation is constant on each positive-mass block, with its weighted mean, and preserves every block integral. A zero-mass block is only determined almost surely: return a.s._arbitrary, never divide by zero. Use exact reduced fractions with positive denominators, omitting /1 for integers. Give (E_X,E_conditional,equal?,tower_to_trivial_sigma_algebra).

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 · calculation

Before

conditional model whole mass sum := sum(8/49, 20/49, 6/49, 15/49)

After

conditional model whole mass sum = 1

Conditions: none

Compute exactly from original roles,complete pairings and established intermediates,retaining denominators,signs and zeros.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001

S002 · implies

Before

conditional model:raw aligned masses=[[8, 49], [20, 49], [6, 49], [15, 49]]

After

normalized masses=[8/49, 20/49, 6/49, 15/49];nonnegative=Yes;total=1

Conditions: none

First qualify nonnegativity and exact unit total on one complete finite probability model.Retain zero-mass atoms;do not assume uniformity or substitute another model.

Step identifiers and dependencies

Rule: whole_finite_probability_law_not_uniform_assumption · Uses: G001, S001

S003 · implies

Before

same outcome indices=[0, 1, 2, 3];X values=[10, -2, 24, -10];block labels=[0, 1, 1, 2]

After

distinct conditioning labels in increasing order=[0, 1, 2]

Conditions: none

Each label fiber is a conditioning block.Labels need not be consecutive.Sort summaries by label but retain original outcome indices within blocks;labels are not array positions.

Step identifiers and dependencies

Rule: conditional_partition_same_space_original_indices · Uses: G001, S002

S004 · calculation

Before

block0 mass := sum(8/49)

After

block0 mass = 8/49

Conditions: none

Compute exactly from original roles,complete pairings and established intermediates,retaining denominators,signs and zeros.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S003

S005 · calculation

Before

block0 atom0 weighted X := mul(8/49, 10)

After

block0 atom0 weighted X = 80/49

Conditions: none

Compute exactly from original roles,complete pairings and established intermediates,retaining denominators,signs and zeros.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S004

S006 · calculation

Before

block0 original weighted integral := sum(80/49)

After

block0 original weighted integral = 80/49

Conditions: none

Compute exactly from original roles,complete pairings and established intermediates,retaining denominators,signs and zeros.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S005

S007 · calculation

Before

block0 positive-mass conditional mean := div(80/49, 8/49)

After

block0 positive-mass conditional mean = 10

Conditions: none

Compute exactly from original roles,complete pairings and established intermediates,retaining denominators,signs and zeros.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S006

S008 · implies

Before

block label=0;indices=[0];positive mass=8/49;weighted integral=80/49

After

block-constant conditional value=10

Conditions: none

Divide the weighted integral by mass only when mass is positive.A zero mean remains the determined numeric value0,not a null-block marker.Copy the same value to every atom in the block.

Step identifiers and dependencies

Rule: positive_block_mean_including_zero_mean · Uses: G001, S007

S009 · calculation

Before

block1 mass := sum(20/49, 6/49)

After

block1 mass = 26/49

Conditions: none

Compute exactly from original roles,complete pairings and established intermediates,retaining denominators,signs and zeros.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S008

S010 · calculation

Before

block1 atom1 weighted X := mul(20/49, -2)

After

block1 atom1 weighted X = -40/49

Conditions: none

Compute exactly from original roles,complete pairings and established intermediates,retaining denominators,signs and zeros.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S009

S011 · calculation

Before

block1 atom2 weighted X := mul(6/49, 24)

After

block1 atom2 weighted X = 144/49

Conditions: none

Compute exactly from original roles,complete pairings and established intermediates,retaining denominators,signs and zeros.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S010

S012 · calculation

Before

block1 original weighted integral := sum(-40/49, 144/49)

After

block1 original weighted integral = 104/49

Conditions: none

Compute exactly from original roles,complete pairings and established intermediates,retaining denominators,signs and zeros.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S011

S013 · calculation

Before

block1 positive-mass conditional mean := div(104/49, 26/49)

After

block1 positive-mass conditional mean = 4

Conditions: none

Compute exactly from original roles,complete pairings and established intermediates,retaining denominators,signs and zeros.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S012

S014 · implies

Before

block label=1;indices=[1, 2];positive mass=26/49;weighted integral=104/49

After

block-constant conditional value=4

Conditions: none

Divide the weighted integral by mass only when mass is positive.A zero mean remains the determined numeric value0,not a null-block marker.Copy the same value to every atom in the block.

Step identifiers and dependencies

Rule: positive_block_mean_including_zero_mean · Uses: G001, S013

S015 · calculation

Before

block2 mass := sum(15/49)

After

block2 mass = 15/49

Conditions: none

Compute exactly from original roles,complete pairings and established intermediates,retaining denominators,signs and zeros.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S014

S016 · calculation

Before

block2 atom3 weighted X := mul(15/49, -10)

After

block2 atom3 weighted X = -150/49

Conditions: none

Compute exactly from original roles,complete pairings and established intermediates,retaining denominators,signs and zeros.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S015

S017 · calculation

Before

block2 original weighted integral := sum(-150/49)

After

block2 original weighted integral = -150/49

Conditions: none

Compute exactly from original roles,complete pairings and established intermediates,retaining denominators,signs and zeros.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S016

S018 · calculation

Before

block2 positive-mass conditional mean := div(-150/49, 15/49)

After

block2 positive-mass conditional mean = -10

Conditions: none

Compute exactly from original roles,complete pairings and established intermediates,retaining denominators,signs and zeros.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S017

S019 · implies

Before

block label=2;indices=[3];positive mass=15/49;weighted integral=-150/49

After

block-constant conditional value=-10

Conditions: none

Divide the weighted integral by mass only when mass is positive.A zero mean remains the determined numeric value0,not a null-block marker.Copy the same value to every atom in the block.

Step identifiers and dependencies

Rule: positive_block_mean_including_zero_mean · Uses: G001, S018

S020 · calculation

Before

total original expectation := sum(80/49, 104/49, -150/49)

After

total original expectation = 34/49

Conditions: none

Compute exactly from original roles,complete pairings and established intermediates,retaining denominators,signs and zeros.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S019

S021 · calculation

Before

total expectation block0 conditional integral := mul(8/49, 10)

After

total expectation block0 conditional integral = 80/49

Conditions: none

Compute exactly from original roles,complete pairings and established intermediates,retaining denominators,signs and zeros.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S020

S022 · calculation

Before

total expectation block1 conditional integral := mul(26/49, 4)

After

total expectation block1 conditional integral = 104/49

Conditions: none

Compute exactly from original roles,complete pairings and established intermediates,retaining denominators,signs and zeros.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S021

S023 · calculation

Before

total expectation block2 conditional integral := mul(15/49, -10)

After

total expectation block2 conditional integral = -150/49

Conditions: none

Compute exactly from original roles,complete pairings and established intermediates,retaining denominators,signs and zeros.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S022

S024 · calculation

Before

total conditional expectation := sum(80/49, 104/49, -150/49)

After

total conditional expectation = 34/49

Conditions: none

Compute exactly from original roles,complete pairings and established intermediates,retaining denominators,signs and zeros.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S023

S025 · implies

Before

all conditioning blocks partition the same carrier;E_X=34/49;E_conditional=34/49

After

equal=Yes;tower_to_trivial_sigma_algebra

Conditions: none

Sum the blockwise integral identities to obtain total expectation equality.This is the tower consequence to the trivial sigma-algebra,not a reverse substitution for measurability and every block obligation.

Step identifiers and dependencies

Rule: total_expectation_consequence_not_whole_definition · 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 — Recompute total conditional expectation with exact rational arithmetic, not rounded decimals.
  • S023 · premise_and_result_audit — Recompute total expectation block2 conditional integral with exact rational arithmetic, not rounded decimals.
  • S022 · premise_and_result_audit — Recompute total expectation block1 conditional integral with exact rational arithmetic, not rounded decimals.
  • S021 · premise_and_result_audit — Recompute total expectation block0 conditional integral with exact rational arithmetic, not rounded decimals.
  • S020 · premise_and_result_audit — Recompute total original expectation 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 — Recompute block2 positive-mass conditional mean with exact rational arithmetic, not rounded decimals.
  • S017 · premise_and_result_audit — Recompute block2 original weighted integral with exact rational arithmetic, not rounded decimals.
  • S016 · premise_and_result_audit — Recompute block2 atom3 weighted X with exact rational arithmetic, not rounded decimals.
  • S015 · premise_and_result_audit — Recompute block2 mass with exact rational arithmetic, not rounded decimals.
  • S014 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S013 · premise_and_result_audit — Recompute block1 positive-mass conditional mean with exact rational arithmetic, not rounded decimals.
  • S012 · premise_and_result_audit — Recompute block1 original weighted integral with exact rational arithmetic, not rounded decimals.
  • S011 · premise_and_result_audit — Recompute block1 atom2 weighted X with exact rational arithmetic, not rounded decimals.
  • S010 · premise_and_result_audit — Recompute block1 atom1 weighted X with exact rational arithmetic, not rounded decimals.
  • S009 · premise_and_result_audit — Recompute block1 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 block0 positive-mass conditional mean with exact rational arithmetic, not rounded decimals.
  • S006 · premise_and_result_audit — Recompute block0 original weighted integral with exact rational arithmetic, not rounded decimals.
  • S005 · premise_and_result_audit — Recompute block0 atom0 weighted X with exact rational arithmetic, not rounded decimals.
  • S004 · premise_and_result_audit — Recompute block0 mass with exact rational arithmetic, not rounded decimals.
  • 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 — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S001 · premise_and_result_audit — Recompute conditional model whole mass sum with exact rational arithmetic, not rounded decimals.

Result

(34/49, 34/49, Yes, tower_to_trivial_sigma_algebra)

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: 7019b3fb6d0ac6a72f4869c94eb5fbd85ae596ffd6f13e3b3df266326bf50368
  • candidate record SHA-256: 0a5ba969ebf42aa414f6d1974935af6ae72a2feb138961e438a0eda5930dc784
  • semantic review receipt SHA-256: e49bf5eaa968c09ebac4ad538ce58251671ed922c957cee1471cfc7b68934bfe
  • question-first witness SHA-256: a7976057c26051fab92342fc95d48af224466c0e1e4ab6ae4c8811c02772e6da
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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