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R0056-28704 · q-20261007-advance-20261008-r01-sequence-limit-0054
For an arbitrary fixed real L, u(n)=L+(-4)/(n+4) on natural indices starting at zero, with d=4≥1. With ε=4/1>0 and candidate N=0, does every n≥N have |u(n)−L|<ε, including n=N?
G001 — For an arbitrary fixed real L, u(n)=L+(-4)/(n+4) on natural indices starting at zero, with d=4≥1. With ε=4/1>0 and candidate N=0, does every n≥N have |u(n)−L|<ε, including n=N?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.
Before
source roles = [qf-sequence-limit-cutoff-validity, cutoff_validity]
After
derived = [strict_all_n_ge_N_tail_validity]
Conditions: none
Use the declared scalar/set/Yes-No/fraction answer role;integer fractions retain/1.Do not add an undeclared domain or change original bilingual data,formulas or questions.
Rule: R56_source_answer_role_and_EXACT_family_interface · Uses: G001
Before
source roles = [-4, 4, naturals_from_zero]
After
derived = [4, u(n)=L+c/(n+d), |u(n)-L|=|c|/(n+d)]
Conditions: none
The premise is the WHOLE law for every n>=0,not a finite prefix.With d>0,the denominator is positive and increasing.Subtract L before taking the absolute value.In error/cutoff tasks L is an arbitrary fixed real,not an invented input parameter.
Rule: Sequence_WHOLE_law_and_positive_increasing_denominator · Uses: G001, S001
Before
Sequence ORIGINAL absolute c times epsilon denominator := mul(4, 1)
After
Sequence ORIGINAL absolute c times epsilon denominator = 4
Conditions: none
Perform exact rational arithmetic on the ORIGINAL roles.SAFE bounds raw inputs only;derived integers are unbounded and never approximated by floats.
Rule: exact_rational_arithmetic · Uses: G001, S002
Before
source roles = [4, 4]
After
derived = [1, 0, left=quot*eps_n+rem, 0<=rem<eps_n]
Conditions: none
Because eps_n>0,integer division yields the exact floor and remainder.No floating rounding or ceil replacement is allowed.Derived products/quotients may exceed SAFE;the raw inputs alone are SAFE-bounded.
Rule: Sequence_EXACT_floor_quotient_remainder_NO_float_or_ceil · Uses: G001, S003
Before
Sequence cutoff ORIGINAL N plus d := sum(0, 4)
After
Sequence cutoff ORIGINAL N plus d = 4
Conditions: none
Perform exact rational arithmetic on the ORIGINAL roles.SAFE bounds raw inputs only;derived integers are unbounded and never approximated by floats.
Rule: exact_rational_arithmetic · Uses: G001, S004
Before
Sequence cutoff ORIGINAL epsilon numerator times N plus d := mul(4, 4)
After
Sequence cutoff ORIGINAL epsilon numerator times N plus d = 16
Conditions: none
Perform exact rational arithmetic on the ORIGINAL roles.SAFE bounds raw inputs only;derived integers are unbounded and never approximated by floats.
Rule: exact_rational_arithmetic · Uses: G001, S005
Before
source roles = [-4, 4, 4, 1, 0, 4, 16]
After
derived = [Yes, Yes]
Conditions: none
Test STRICT < at N;equality is No.Since denominators increase for n>=N,success at N gives the whole tail,and failure at N itself is a counterexample.Do not test N+1 instead,or infer minimality from mere validity.
Rule: Sequence_cutoff_STRICT_cross_product_at_N_IFF_ALL_tail · Uses: G001, S006
S007 · premise_and_result_audit — Reverse-check EACH original datum and premise,retaining indices,signs and strict/non-strict boundaries.A correct final answer cannot replace the derivation obligations.This is candidate teaching/exact checking,not formal proof or publication clearance.S006 · premise_and_result_audit — Recompute Sequence cutoff ORIGINAL epsilon numerator times N plus d with exact rational arithmetic, not rounded decimals.S005 · premise_and_result_audit — Recompute Sequence cutoff ORIGINAL N plus d with exact rational arithmetic, not rounded decimals.S004 · premise_and_result_audit — Reverse-check EACH original datum and premise,retaining indices,signs and strict/non-strict boundaries.A correct final answer cannot replace the derivation obligations.This is candidate teaching/exact checking,not formal proof or publication clearance.S003 · premise_and_result_audit — Recompute Sequence ORIGINAL absolute c times epsilon denominator with exact rational arithmetic, not rounded decimals.S002 · premise_and_result_audit — Reverse-check EACH original datum and premise,retaining indices,signs and strict/non-strict boundaries.A correct final answer cannot replace the derivation obligations.This is candidate teaching/exact checking,not formal proof or publication clearance.S001 · premise_and_result_audit — Reverse-check EACH original datum and premise,retaining indices,signs and strict/non-strict boundaries.A correct final answer cannot replace the derivation obligations.This is candidate teaching/exact checking,not formal proof or publication clearance.Yes
The full substitutions and premise checks give the original answer; source identity,format and status are unchanged.
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.
input commit: 0f7be61e2c22317a4075561dc822c87d881a50dboriginal question SHA-256: cf310970617b2f749bae40c4e0855bb01793ab52ac9513dd2adcef0c4f4a48adcandidate record SHA-256: 8d2a7d3fee4976edb271bc45400ba76afc0aa290ccc65a4c787ce4698af6a31bsemantic review receipt SHA-256: 8bbda4edbed7078634ae88342998c79bcfb95de96187fac119c3b08e0adb0bc8question-first witness SHA-256: 3edafa72d63d16a22414892b55806430e0a25b15b926d04f312550179607759fLean: NOT_RUN · human review: NOT_PERFORMED