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Question 14177: 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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R0027-14177 · q-20261014-advance-20261029-r04-conditional-expectation-0077

Original question and givens

Use one complete finite probability space with outcome indices 0 through 3, aligned masses=[30/49, 5/49, 12/49, 2/49], values X=[-11, -2, 3, 11], and conditioning-block labels=[0, 0, 1, 1]. 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=[30/49, 5/49, 12/49, 2/49], values X=[-11, -2, 3, 11], and conditioning-block labels=[0, 0, 1, 1]. 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(30/49, 5/49, 12/49, 2/49)

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=[[30, 49], [5, 49], [12, 49], [2, 49]]

After

normalized masses=[30/49, 5/49, 12/49, 2/49];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=[-11, -2, 3, 11];block labels=[0, 0, 1, 1]

After

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

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(30/49, 5/49)

After

block0 mass = 5/7

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(30/49, -11)

After

block0 atom0 weighted X = -330/49

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 atom1 weighted X := mul(5/49, -2)

After

block0 atom1 weighted X = -10/49

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 original weighted integral := sum(-330/49, -10/49)

After

block0 original weighted integral = -340/49

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, S006

S008 · calculation

Before

block0 positive-mass conditional mean := div(-340/49, 5/7)

After

block0 positive-mass conditional mean = -68/7

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, S007

S009 · implies

Before

block label=0;indices=[0, 1];positive mass=5/7;weighted integral=-340/49

After

block-constant conditional value=-68/7

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, S008

S010 · calculation

Before

block1 mass := sum(12/49, 2/49)

After

block1 mass = 2/7

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(12/49, 3)

After

block1 atom2 weighted X = 36/49

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 atom3 weighted X := mul(2/49, 11)

After

block1 atom3 weighted X = 22/49

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 original weighted integral := sum(36/49, 22/49)

After

block1 original weighted integral = 58/49

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, S012

S014 · calculation

Before

block1 positive-mass conditional mean := div(58/49, 2/7)

After

block1 positive-mass conditional mean = 29/7

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, S013

S015 · implies

Before

block label=1;indices=[2, 3];positive mass=2/7;weighted integral=58/49

After

block-constant conditional value=29/7

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, S014

S016 · calculation

Before

total original expectation := sum(-340/49, 58/49)

After

total original expectation = -282/49

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

total expectation block0 conditional integral := mul(5/7, -68/7)

After

total expectation block0 conditional integral = -340/49

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

total expectation block1 conditional integral := mul(2/7, 29/7)

After

total expectation block1 conditional integral = 58/49

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, S017

S019 · calculation

Before

total conditional expectation := sum(-340/49, 58/49)

After

total conditional expectation = -282/49

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, S018

S020 · implies

Before

all conditioning blocks partition the same carrier;E_X=-282/49;E_conditional=-282/49

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, S019

Reverse checks

  • 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 conditional expectation with exact rational arithmetic, not rounded decimals.
  • S018 · premise_and_result_audit — Recompute total expectation block1 conditional integral with exact rational arithmetic, not rounded decimals.
  • S017 · premise_and_result_audit — Recompute total expectation block0 conditional integral with exact rational arithmetic, not rounded decimals.
  • S016 · premise_and_result_audit — Recompute total original expectation with exact rational arithmetic, not rounded decimals.
  • S015 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S014 · premise_and_result_audit — Recompute block1 positive-mass conditional mean with exact rational arithmetic, not rounded decimals.
  • S013 · premise_and_result_audit — Recompute block1 original weighted integral with exact rational arithmetic, not rounded decimals.
  • S012 · premise_and_result_audit — Recompute block1 atom3 weighted X 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 mass with exact rational arithmetic, not rounded decimals.
  • S009 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S008 · premise_and_result_audit — Recompute block0 positive-mass conditional mean with exact rational arithmetic, not rounded decimals.
  • S007 · premise_and_result_audit — Recompute block0 original weighted integral with exact rational arithmetic, not rounded decimals.
  • S006 · premise_and_result_audit — Recompute block0 atom1 weighted X 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

(-282/49, -282/49, 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: 69e1bfbb1e613c41226609b12fc9b06a6579d32d00be6c5a4587050ec719526a
  • candidate record SHA-256: 534f27ed3e48eb070269c6f5e80aeac97d4fbe4090682340485c587f074eba66
  • semantic review receipt SHA-256: e49bf5eaa968c09ebac4ad538ce58251671ed922c957cee1471cfc7b68934bfe
  • question-first witness SHA-256: a7976057c26051fab92342fc95d48af224466c0e1e4ab6ae4c8811c02772e6da
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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