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Question 14193: 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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R0027-14193 · q-20261014-advance-20261029-r04-conditional-expectation-0093

Original question and givens

Use one complete finite probability space with outcome indices 0 through 3, aligned masses=[12/49, 16/49, 9/49, 12/49], values X=[5, 0, 19, -5], 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=[12/49, 16/49, 9/49, 12/49], values X=[5, 0, 19, -5], 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(12/49, 16/49, 9/49, 12/49)

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=[[12, 49], [16, 49], [9, 49], [12, 49]]

After

normalized masses=[12/49, 16/49, 9/49, 12/49];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=[5, 0, 19, -5];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(12/49, 16/49)

After

block0 mass = 4/7

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(12/49, 5)

After

block0 atom0 weighted X = 60/49

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(16/49, 0)

After

block0 atom1 weighted X = 0

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(60/49, 0)

After

block0 original weighted integral = 60/49

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(60/49, 4/7)

After

block0 positive-mass conditional mean = 15/7

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=4/7;weighted integral=60/49

After

block-constant conditional value=15/7

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(9/49, 12/49)

After

block1 mass = 3/7

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(9/49, 19)

After

block1 atom2 weighted X = 171/49

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(12/49, -5)

After

block1 atom3 weighted X = -60/49

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(171/49, -60/49)

After

block1 original weighted integral = 111/49

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(111/49, 3/7)

After

block1 positive-mass conditional mean = 37/7

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=3/7;weighted integral=111/49

After

block-constant conditional value=37/7

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(60/49, 111/49)

After

total original expectation = 171/49

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(4/7, 15/7)

After

total expectation block0 conditional integral = 60/49

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(3/7, 37/7)

After

total expectation block1 conditional integral = 111/49

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(60/49, 111/49)

After

total conditional expectation = 171/49

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=171/49;E_conditional=171/49

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

(171/49, 171/49, 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: 70be38823ac86d115ffce3b31a00c44cb5f9c7b272fdd5ef99888d3354a5f13d
  • candidate record SHA-256: e49d44d39b98f4656df632211c8c38c65f295b70326aaa304b6038b308dc94be
  • semantic review receipt SHA-256: e49bf5eaa968c09ebac4ad538ce58251671ed922c957cee1471cfc7b68934bfe
  • question-first witness SHA-256: a7976057c26051fab92342fc95d48af224466c0e1e4ab6ae4c8811c02772e6da
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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