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Question 23668: A Zero Symmetric Principal Value Does Not Give Ordinary Improper Convergence

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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R0046-23668 · q-20261014-advance-20261112-r04-improper-integral-0093

Original question and givens

Use f(x)=1/x on the real line with singularity0, symmetric cutoff B=19 and exclusion epsilon=1/19. Give (integrand, domain, cutoff, epsilon, symmetric_truncated_value, symmetric_principal_value_zero, ordinary_improper_converges, finite_cutoffs_certificate, boundary).

  • G001 — Use f(x)=1/x on the real line with singularity0, symmetric cutoff B=19 and exclusion epsilon=1/19. Give (integrand, domain, cutoff, epsilon, symmetric_truncated_value, symmetric_principal_value_zero, ordinary_improper_converges, finite_cutoffs_certificate, boundary).

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=improper-principal-value-boundary;original snapshot and mathematics retained

After

explicit ordered source output fields=[integrand, domain, cutoff, epsilon, symmetric_truncated_value, symmetric_principal_value_zero, ordinary_improper_converges, finite_cutoffs_certificate, boundary]

Conditions: none

Keep the source snapshot while listing ordered fields without JavaScript.Radius uses its original mode to select6 or11 fields without padding;distinguish nonclaims from actual negations.

Step identifiers and dependencies

Rule: source_ordered_interface_explicit_without_javascript · Uses: G001

S002 · implies

Before

ORIGINAL f(x)=1/x;B=19>=2;epsilon=1/19<=1/2

After

for EVERY B>epsilon>0,positive truncated integral=log(B)-log(epsilon),negative truncated integral=its negative;sum0,so symmetric principal value0

Conditions: none

Substitute x=-u on the negative side to obtain the opposite truncated integral.This holds for every valid symmetric pair,not just the displayed cutoffs.

Step identifiers and dependencies

Rule: improper_PV_exact_odd_symmetric_truncations_ALL_cutoffs · Uses: G001, S001

S003 · implies

Before

ORIGINAL whole integrand1/x on both infinite ends and both sides of singularity0

After

integral_epsilon^1=-log(epsilon) tends+infinity and integral_-1^-epsilon tends-infinity;integral_1^B=log(B) tends+infinity and integral_-B^-1 tends-infinity;ordinary improper convergence=No,finite_cutoffs_certificate=No

Conditions: none

Ordinary improper integration requires finite limits separately at every infinite end and singular side.+infinity and−infinity cannot be cancelled to define it.PV0 and finite truncations0 do not replace these obligations.

Step identifiers and dependencies

Rule: improper_REQUIRED_independent_limits_diverge_despite_PV0 · Uses: G001, S002

Reverse checks

  • 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 — Check against the original data and this step's premises; a one-way implication is not an equivalence.

Result

(f(x)=1/x, (-infinity,infinity) with singularity at 0, 19, 1/19, 0, Yes, No, No, symmetric_principal_value_is_zero_but_the_required_one_sided_limits_diverge_and_finite_cutoffs_do_not_prove_convergence)

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: b0d79ade956d900d3164c71e8ad60544810487eca17f73717b419a4923db8bdc
  • candidate record SHA-256: dc70acc433a1b526117b89c75bb1893ec93c5ce1705fe34b798d98eca720f41a
  • semantic review receipt SHA-256: a7c0d888ade6d307703c4222c4137c78c0d2448babdcba2fa3446fe6fdd343c1
  • question-first witness SHA-256: c9571f97a37d503ad6a61034cc00108543a05c37ef246d1c4962f55136a3de02
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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