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Question 21591: Grammar Qualification Requires Complete Alphabets, Start and Productions

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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R0042-21591 · q-20261014-advance-20261109-r07-context-free-grammar-0016

Original question and givens

Use the complete finite grammar: nonterminals=[S15, A15], terminals=[a15, b15], start=S15, productions=[[S15, [a15, A15]], [A15, [b15, A15]], [A15, []]] and allow_epsilon=true. Alphabets must be unique and disjoint, the start belongs to nonterminals, and each production [lhs,rhs] has exactly one nonterminal lhs and a finite legal-symbol rhs. Empty rhs is permitted only under the explicit epsilon convention. Keep original symbol and production order. Give (nonterminals, terminals, start, productions, allow_epsilon, grammar_qualified, certificate).

  • G001 — Use the complete finite grammar: nonterminals=[S15, A15], terminals=[a15, b15], start=S15, productions=[[S15, [a15, A15]], [A15, [b15, A15]], [A15, []]] and allow_epsilon=true. Alphabets must be unique and disjoint, the start belongs to nonterminals, and each production [lhs,rhs] has exactly one nonterminal lhs and a finite legal-symbol rhs. Empty rhs is permitted only under the explicit epsilon convention. Keep original symbol and production order. Give (nonterminals, terminals, start, productions, allow_epsilon, grammar_qualified, 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=cfg-qualification;original snapshot and mathematics retained

After

explicit ordered source output fields=[nonterminals, terminals, start, productions, allow_epsilon, grammar_qualified, certificate]

Conditions: none

Keep the original historical interface marker while listing ordered source fields without JavaScript.Tags are not additional evidence;fixed No markers retain their source claim scope.

Step identifiers and dependencies

Rule: source_ordered_interface_explicit_without_javascript · Uses: G001

S002 · implies

Before

ORIGINAL production index=0;lhs=S15,rhs=[a15, A15];N=[S15, A15],T=[a15, b15],allow_epsilon=Yes

After

lhs is ONE declared nonterminal;every rhs symbol legal;empty rhs accepted ONLY under the explicit epsilon convention;original production position retained

Conditions: none

Each production has one nonterminal on the left.Check every right-hand symbol and the explicit epsilon convention.Duplicate production positions may exist;sorting them would change first-witness indices.

Step identifiers and dependencies

Rule: cfg_each_original_production_single_nonterminal_legal_rhs · Uses: G001, S001

S003 · implies

Before

ORIGINAL production index=1;lhs=A15,rhs=[b15, A15];N=[S15, A15],T=[a15, b15],allow_epsilon=Yes

After

lhs is ONE declared nonterminal;every rhs symbol legal;empty rhs accepted ONLY under the explicit epsilon convention;original production position retained

Conditions: none

Each production has one nonterminal on the left.Check every right-hand symbol and the explicit epsilon convention.Duplicate production positions may exist;sorting them would change first-witness indices.

Step identifiers and dependencies

Rule: cfg_each_original_production_single_nonterminal_legal_rhs · Uses: G001, S002

S004 · implies

Before

ORIGINAL production index=2;lhs=A15,rhs=[];N=[S15, A15],T=[a15, b15],allow_epsilon=Yes

After

lhs is ONE declared nonterminal;every rhs symbol legal;empty rhs accepted ONLY under the explicit epsilon convention;original production position retained

Conditions: none

Each production has one nonterminal on the left.Check every right-hand symbol and the explicit epsilon convention.Duplicate production positions may exist;sorting them would change first-witness indices.

Step identifiers and dependencies

Rule: cfg_each_original_production_single_nonterminal_legal_rhs · Uses: G001, S003

S005 · implies

Before

ORIGINAL unique disjoint N=[S15, A15],T=[a15, b15];start=S15;complete productions=[[S15, [a15, A15]], [A15, [b15, A15]], [A15, []]];allow_epsilon=Yes

After

start belongs to nonterminals;finite grammar qualified;NO derivation,membership,regularity,unambiguity or PDA equivalence inferred

Conditions: none

Grammar qualification alone supplies no derivation for a word and no regularity or unambiguity claim.Retain both alphabet orders.

Step identifiers and dependencies

Rule: cfg_qualified_alphabets_start_not_language_property · Uses: G001, S004

Reverse checks

  • S005 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S004 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • 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

([S15, A15], [a15, b15], S15, [[S15, [a15, A15]], [A15, [b15, A15]], [A15, []]], Yes, Yes, finite_disjoint_alphabets_single_nonterminal_lhs)

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: 92a06eb7c3e7bea500e7e0022110265d89ae3650326a2c87d707de99cbdb7cd1
  • candidate record SHA-256: 596db8686c663647fc913bda653ea9b0f9b51461d5b1f95af795c54c1a1c68d3
  • semantic review receipt SHA-256: dd44555041dfbb6fe9936aa00b9a5f8c5982c2784ef61dd0cbd5d1a303a49c1a
  • question-first witness SHA-256: 9a6011263f6ac53b9a1fd57addf2f3e2f6088b54802c539f332d689480dc2d17
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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