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Question 22818: Strictly Ordered Query Points May Have Equal CDF Values

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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R0044-22818 · q-20261014-advance-20261111-r04-continuous-real-distribution-function-0043

Original question and givens

Use strictly increasing knots=[-19, 0, 19], aligned exact values=[0, 18/19, 1], linear interpolation between knots, constant0 to the left and constant1 to the right. Knot values must be nondecreasing from0 to1. This declares a whole continuous CDF, not just finite samples; flat intervals are allowed. Exact query_points=[-20, 0, 20] must be strictly increasing. Give (query_value_rows, nondecreasing_sample, left_tail_value, right_tail_value, certificate).

  • G001 — Use strictly increasing knots=[-19, 0, 19], aligned exact values=[0, 18/19, 1], linear interpolation between knots, constant0 to the left and constant1 to the right. Knot values must be nondecreasing from0 to1. This declares a whole continuous CDF, not just finite samples; flat intervals are allowed. Exact query_points=[-20, 0, 20] must be strictly increasing. Give (query_value_rows, nondecreasing_sample, left_tail_value, right_tail_value, 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=contcdf-monotone-endpoint-audit;original snapshot and mathematics retained

After

explicit ordered source output fields=[query_value_rows, nondecreasing_sample, left_tail_value, right_tail_value, certificate]

Conditions: none

Keep the historical interface marker and list ordered source fields without JavaScript.Tags are not additional evidence;fixed No markers retain their scope.The ordering helper supplies protocol order,not mathematical correctness.

Step identifiers and dependencies

Rule: source_ordered_interface_explicit_without_javascript · Uses: G001

S002 · calculation

Before

CDF segment0 positive knot width := sub(0, -19)

After

CDF segment0 positive knot width = 19

Conditions: none

Substitute original roles,indices and established intermediates exactly,not floating-point approximations or another question's data.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S001

S003 · calculation

Before

CDF segment0 nonnegative value increment := sub(18/19, 0)

After

CDF segment0 nonnegative value increment = 18/19

Conditions: none

Substitute original roles,indices and established intermediates exactly,not floating-point approximations or another question's data.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S002

S004 · calculation

Before

CDF segment0 exact nonnegative slope := div(18/19, 19)

After

CDF segment0 exact nonnegative slope = 18/361

Conditions: none

Substitute original roles,indices and established intermediates exactly,not floating-point approximations or another question's data.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S003

S005 · calculation

Before

CDF segment1 positive knot width := sub(19, 0)

After

CDF segment1 positive knot width = 19

Conditions: none

Substitute original roles,indices and established intermediates exactly,not floating-point approximations or another question's data.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S004

S006 · calculation

Before

CDF segment1 nonnegative value increment := sub(1, 18/19)

After

CDF segment1 nonnegative value increment = 1/19

Conditions: none

Substitute original roles,indices and established intermediates exactly,not floating-point approximations or another question's data.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S005

S007 · calculation

Before

CDF segment1 exact nonnegative slope := div(1/19, 19)

After

CDF segment1 exact nonnegative slope = 1/361

Conditions: none

Substitute original roles,indices and established intermediates exactly,not floating-point approximations or another question's data.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S006

S008 · implies

Before

ORIGINAL strictly increasing knots=[-19, 0, 19];aligned exact nondecreasing values=[0, 18/19, 1];ALL [width,height,slope] rows=[[19, 18/19, 18/361], [19, 1/19, 1/361]]

After

declare linear interpolation on EVERY segment,constant0 left and1 right;shared knot values make joins continuous;all slopes>=0 allow flats;continuous implies right-continuous and endpoints give limits0/1

Conditions: none

These are properties of the declared whole interpolation law,not inferences from finite knot/query observations.Nonnegative slopes and matching joins give monotonicity and continuity;constant tails give the limits.This PL example may have a density without every continuous CDF having one.

Step identifiers and dependencies

Rule: contcdf_WHOLE_piecewise_law_continuous_flat_monotone_tails · Uses: G001, S007

S009 · implies

Before

CDF ORIGINAL ordered query0:ORIGINAL exact query x=-20;knots=[-19, 0, 19];values=[0, 18/19, 1]

After

case=left constant tail including first knot;source interval index=null;F(x)=0;this is CDF value,NOT singleton mass

Conditions: none

Evaluate the original query in its constant tail or first containing interval.The formulas agree at shared knots.F(x) is cumulative probability,not P(X=x).

Step identifiers and dependencies

Rule: contcdf_actual_query_exact_branch_not_empirical_mass · Uses: G001, S008

S010 · calculation

Before

CDF ORIGINAL ordered query1 ORIGINAL query minus left knot := sub(0, -19)

After

CDF ORIGINAL ordered query1 ORIGINAL query minus left knot = 19

Conditions: none

Substitute original roles,indices and established intermediates exactly,not floating-point approximations or another question's data.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S009

S011 · calculation

Before

CDF ORIGINAL ordered query1 exact interval fraction := div(19, 19)

After

CDF ORIGINAL ordered query1 exact interval fraction = 1

Conditions: none

Substitute original roles,indices and established intermediates exactly,not floating-point approximations or another question's data.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S010

S012 · calculation

Before

CDF ORIGINAL ordered query1 fraction times ORIGINAL value increment := mul(1, 18/19)

After

CDF ORIGINAL ordered query1 fraction times ORIGINAL value increment = 18/19

Conditions: none

Substitute original roles,indices and established intermediates exactly,not floating-point approximations or another question's data.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S011

S013 · calculation

Before

CDF ORIGINAL ordered query1 plus ORIGINAL left-knot value := sum(0, 18/19)

After

CDF ORIGINAL ordered query1 plus ORIGINAL left-knot value = 18/19

Conditions: none

Substitute original roles,indices and established intermediates exactly,not floating-point approximations or another question's data.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S012

S014 · implies

Before

CDF ORIGINAL ordered query1:ORIGINAL exact query x=0;knots=[-19, 0, 19];values=[0, 18/19, 1]

After

case=FIRST source interval containing query,including shared knot;source interval index=0;F(x)=18/19;this is CDF value,NOT singleton mass

Conditions: none

Evaluate the original query in its constant tail or first containing interval.The formulas agree at shared knots.F(x) is cumulative probability,not P(X=x).

Step identifiers and dependencies

Rule: contcdf_actual_query_exact_branch_not_empirical_mass · Uses: G001, S013

S015 · implies

Before

CDF ORIGINAL ordered query2:ORIGINAL exact query x=20;knots=[-19, 0, 19];values=[0, 18/19, 1]

After

case=right constant tail including last knot;source interval index=null;F(x)=1;this is CDF value,NOT singleton mass

Conditions: none

Evaluate the original query in its constant tail or first containing interval.The formulas agree at shared knots.F(x) is cumulative probability,not P(X=x).

Step identifiers and dependencies

Rule: contcdf_actual_query_exact_branch_not_empirical_mass · Uses: G001, S014

S016 · implies

Before

CDF ORIGINAL left-tail check:ORIGINAL exact query x=-20;knots=[-19, 0, 19];values=[0, 18/19, 1]

After

case=left constant tail including first knot;source interval index=null;F(x)=0;this is CDF value,NOT singleton mass

Conditions: none

Evaluate the original query in its constant tail or first containing interval.The formulas agree at shared knots.F(x) is cumulative probability,not P(X=x).

Step identifiers and dependencies

Rule: contcdf_actual_query_exact_branch_not_empirical_mass · Uses: G001, S015

S017 · implies

Before

CDF ORIGINAL right-tail check:ORIGINAL exact query x=20;knots=[-19, 0, 19];values=[0, 18/19, 1]

After

case=right constant tail including last knot;source interval index=null;F(x)=1;this is CDF value,NOT singleton mass

Conditions: none

Evaluate the original query in its constant tail or first containing interval.The formulas agree at shared knots.F(x) is cumulative probability,not P(X=x).

Step identifiers and dependencies

Rule: contcdf_actual_query_exact_branch_not_empirical_mass · Uses: G001, S016

S018 · implies

Before

ORIGINAL strictly increasing queries=[-20, 0, 20];exact values=[0, 18/19, 1]

After

NONSTRICT sample value monotonicity=Yes;left tail=0,right tail=1;global monotonicity already proved from the WHOLE law

Conditions: none

Query coordinates must be strictly increasing,but flat segments may give equal CDF values.An empty query list has a vacuous conjunction.Global properties came from the whole law,not this finite list alone.

Step identifiers and dependencies

Rule: contcdf_ordered_queries_allow_EQUAL_values_not_global_sample_proof · Uses: G001, S017

Reverse checks

  • S018 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S017 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • 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 — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • 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 CDF ORIGINAL ordered query1 plus ORIGINAL left-knot value with exact rational arithmetic, not rounded decimals.
  • S012 · premise_and_result_audit — Recompute CDF ORIGINAL ordered query1 fraction times ORIGINAL value increment with exact rational arithmetic, not rounded decimals.
  • S011 · premise_and_result_audit — Recompute CDF ORIGINAL ordered query1 exact interval fraction with exact rational arithmetic, not rounded decimals.
  • S010 · premise_and_result_audit — Recompute CDF ORIGINAL ordered query1 ORIGINAL query minus left knot 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 — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S007 · premise_and_result_audit — Recompute CDF segment1 exact nonnegative slope with exact rational arithmetic, not rounded decimals.
  • S006 · premise_and_result_audit — Recompute CDF segment1 nonnegative value increment with exact rational arithmetic, not rounded decimals.
  • S005 · premise_and_result_audit — Recompute CDF segment1 positive knot width with exact rational arithmetic, not rounded decimals.
  • S004 · premise_and_result_audit — Recompute CDF segment0 exact nonnegative slope with exact rational arithmetic, not rounded decimals.
  • S003 · premise_and_result_audit — Recompute CDF segment0 nonnegative value increment with exact rational arithmetic, not rounded decimals.
  • S002 · premise_and_result_audit — Recompute CDF segment0 positive knot width 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

([[-20, 0], [0, 18/19], [20, 1]], Yes, 0, 1, nondecreasing_with_left_zero_and_right_one_limits)

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: 8b8e0dcdce0be0234709895fb2ea2c877cd433645f8773654337cc4035d2728e
  • candidate record SHA-256: 47796707678faf84c6c9f88d7408ae79feaecc2149579994d3f1d691f609ffa0
  • semantic review receipt SHA-256: 89b8e810eced1a69dbfef28d4b112e829edf156c7905a86e39a3f4958cd75e81
  • question-first witness SHA-256: b2e8b769c463242f05172564ae96e310403eae151e1ec30bcb50be3ffe12cfc7
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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