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Question 17776: Terms Tending to Zero Do Not Make a Harmonic Tail Summable

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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R0034-17776 · q-20261014-advance-20261103-r03-infinite-series-0076

Original question and givens

Use the shifted harmonic terms 1/(n+shift), n=0,1,..., with positive shift=1 and displayed prefix_length=5. Give (shift,prefix_length,terms,terms_tend_zero?,series_converges?,terms_tend_to_zero_but_shifted_harmonic_series_diverges).

  • G001 — Use the shifted harmonic terms 1/(n+shift), n=0,1,..., with positive shift=1 and displayed prefix_length=5. Give (shift,prefix_length,terms,terms_tend_zero?,series_converges?,terms_tend_to_zero_but_shifted_harmonic_series_diverges).

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

harmonic displayed index0 denominator := sum(0, 1)

After

harmonic displayed index0 denominator = 1

Conditions: none

Compute exactly from original roles and established intermediates,retaining denominators,signs,indices and strict conditions.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001

S002 · calculation

Before

harmonic displayed index0 term := div(1, 1)

After

harmonic displayed index0 term = 1

Conditions: none

Compute exactly from original roles and established intermediates,retaining denominators,signs,indices and strict conditions.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S001

S003 · calculation

Before

harmonic displayed index1 denominator := sum(1, 1)

After

harmonic displayed index1 denominator = 2

Conditions: none

Compute exactly from original roles and established intermediates,retaining denominators,signs,indices and strict conditions.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S002

S004 · calculation

Before

harmonic displayed index1 term := div(1, 2)

After

harmonic displayed index1 term = 1/2

Conditions: none

Compute exactly from original roles and established intermediates,retaining denominators,signs,indices and strict conditions.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S003

S005 · calculation

Before

harmonic displayed index2 denominator := sum(2, 1)

After

harmonic displayed index2 denominator = 3

Conditions: none

Compute exactly from original roles and established intermediates,retaining denominators,signs,indices and strict conditions.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S004

S006 · calculation

Before

harmonic displayed index2 term := div(1, 3)

After

harmonic displayed index2 term = 1/3

Conditions: none

Compute exactly from original roles and established intermediates,retaining denominators,signs,indices and strict conditions.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S005

S007 · calculation

Before

harmonic displayed index3 denominator := sum(3, 1)

After

harmonic displayed index3 denominator = 4

Conditions: none

Compute exactly from original roles and established intermediates,retaining denominators,signs,indices and strict conditions.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S006

S008 · calculation

Before

harmonic displayed index3 term := div(1, 4)

After

harmonic displayed index3 term = 1/4

Conditions: none

Compute exactly from original roles and established intermediates,retaining denominators,signs,indices and strict conditions.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S007

S009 · calculation

Before

harmonic displayed index4 denominator := sum(4, 1)

After

harmonic displayed index4 denominator = 5

Conditions: none

Compute exactly from original roles and established intermediates,retaining denominators,signs,indices and strict conditions.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S008

S010 · calculation

Before

harmonic displayed index4 term := div(1, 5)

After

harmonic displayed index4 term = 1/5

Conditions: none

Compute exactly from original roles and established intermediates,retaining denominators,signs,indices and strict conditions.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S009

S011 · implies

Before

shifted harmonic series:DECLARED whole positive tail b_k=1/(k+1),k>=0;shift>0

After

b_k decreases to0:for ANY epsilon>0 choose N with N+shift>1/epsilon,then every k>=N has b_k<epsilon

Conditions: none

Increasing denominators and an Archimedean cutoff supply the all-later bound for every epsilon,not an inference from the displayed prefix.

Step identifiers and dependencies

Rule: harmonic_full_tail_terms_zero_not_observed_prefix · Uses: G001, S010

S012 · implies

Before

shifted harmonic series:same full absolute/positive series over denominators m=1,2,...

After

for every integer j>=0 large enough that2^j>=shift-1,the block m=2^j+1..2^(j+1) has2^j terms each>=1/2^(j+1);each block sum>=1/2;infinitely many disjoint blocks make partial sums unbounded

Conditions: none

Removing finitely many initial terms leaves the dyadic-block argument.Each sufficiently late block contributes at least1/2,so arbitrarily many disjoint blocks force unbounded partial sums.Terms tending to zero do not give a finite limit of partial sums.

Step identifiers and dependencies

Rule: harmonic_shifted_dyadic_blocks_diverge_not_term_limit · Uses: G001, S011

S013 · implies

Before

displayed finite prefix=[1, 1/2, 1/3, 1/4, 1/5];SEPARATE complete harmonic-tail proof retained

After

terms tend to0=Yes;series converges=No;terms_tend_to_zero_but_shifted_harmonic_series_diverges

Conditions: none

The finite list is illustrative.The two infinite claims come separately from the declared full tail and block argument;the necessary term-zero condition is not sufficient.

Step identifiers and dependencies

Rule: series_term_limit_not_partial_sum_limit · Uses: G001, S012

Reverse checks

  • S013 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • 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 — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S010 · premise_and_result_audit — Recompute harmonic displayed index4 term with exact rational arithmetic, not rounded decimals.
  • S009 · premise_and_result_audit — Recompute harmonic displayed index4 denominator with exact rational arithmetic, not rounded decimals.
  • S008 · premise_and_result_audit — Recompute harmonic displayed index3 term with exact rational arithmetic, not rounded decimals.
  • S007 · premise_and_result_audit — Recompute harmonic displayed index3 denominator with exact rational arithmetic, not rounded decimals.
  • S006 · premise_and_result_audit — Recompute harmonic displayed index2 term with exact rational arithmetic, not rounded decimals.
  • S005 · premise_and_result_audit — Recompute harmonic displayed index2 denominator with exact rational arithmetic, not rounded decimals.
  • S004 · premise_and_result_audit — Recompute harmonic displayed index1 term with exact rational arithmetic, not rounded decimals.
  • S003 · premise_and_result_audit — Recompute harmonic displayed index1 denominator with exact rational arithmetic, not rounded decimals.
  • S002 · premise_and_result_audit — Recompute harmonic displayed index0 term with exact rational arithmetic, not rounded decimals.
  • S001 · premise_and_result_audit — Recompute harmonic displayed index0 denominator with exact rational arithmetic, not rounded decimals.

Result

(1, 5, [1, 1/2, 1/3, 1/4, 1/5], Yes, No, terms_tend_to_zero_but_shifted_harmonic_series_diverges)

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: 7bce0ac133013ba642d047eb868c7c131807eb742a825ad576988664424083a1
  • candidate record SHA-256: aaf9631623913a01653bcccbb2f5dc53be986036eb2f768eb5c591fa694a3757
  • semantic review receipt SHA-256: f73d099ebe3ff1c69a5d96f08c75b11b9e5b05120af40cf3ef388fce3b5c5336
  • question-first witness SHA-256: 22675ffb6209b4fea076032b29b96e3dc19aad4244c54493f5f65f5e5d875699
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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