Original question and givens
Use the complete finite nondeterministic PDA: states=[push2, pop2, accept2], input_alphabet=[a2, b2], stack_alphabet=[Z2, A2], start_state=push2, bottom_symbol=Z2, final_states=[accept2], transitions=[[push2, a2, Z2, push2, [Z2, A2]], [push2, a2, A2, push2, [A2, A2]], [push2, b2, A2, pop2, []], [pop2, b2, A2, pop2, []], [push2, null, Z2, accept2, [Z2]], [pop2, null, Z2, accept2, [Z2]]]. Alphabets are unique and pairwise disjoint. Each transition is [from,input symbol or null,required top,to,replacement bottom-to-top]. null is epsilon and consumes no input. Configurations are [state,input position,stack] with bottom first and top last. Preserve the bottom marker and accept only after consuming the entire input in a final state, not by empty stack. Input=[a2, a2, b2, b2], supplied trace=[[push2, 0, [Z2]], [push2, 1, [Z2, A2]], [push2, 2, [Z2, A2, A2]], [pop2, 3, [Z2, A2]], [pop2, 4, [Z2]], [accept2, 4, [Z2]]]. Give (input, trace, transition_indices, valid_run, accepted, step_count, certificate).
G001 — Use the complete finite nondeterministic PDA: states=[push2, pop2, accept2], input_alphabet=[a2, b2], stack_alphabet=[Z2, A2], start_state=push2, bottom_symbol=Z2, final_states=[accept2], transitions=[[push2, a2, Z2, push2, [Z2, A2]], [push2, a2, A2, push2, [A2, A2]], [push2, b2, A2, pop2, []], [pop2, b2, A2, pop2, []], [push2, null, Z2, accept2, [Z2]], [pop2, null, Z2, accept2, [Z2]]]. Alphabets are unique and pairwise disjoint. Each transition is [from,input symbol or null,required top,to,replacement bottom-to-top]. null is epsilon and consumes no input. Configurations are [state,input position,stack] with bottom first and top last. Preserve the bottom marker and accept only after consuming the entire input in a final state, not by empty stack. Input=[a2, a2, b2, b2], supplied trace=[[push2, 0, [Z2]], [push2, 1, [Z2, A2]], [push2, 2, [Z2, A2, A2]], [pop2, 3, [Z2, A2]], [pop2, 4, [Z2]], [accept2, 4, [Z2]]]. Give (input, trace, transition_indices, valid_run, accepted, step_count, certificate).
Step-by-step derivation
S001 · implies
Before
source operation=pda-accepting-run-witness;original snapshot and mathematics retained
After
explicit ordered source output fields=[input, trace, transition_indices, valid_run, accepted, step_count, certificate]
Conditions: none
Retain the historical interface marker and list ordered source fields without JavaScript.MVT fields come from the original mode,without padding or answer-shape inference.Tags and fixed No markers retain their claim scope.
Step identifiers and dependencies
Rule: source_ordered_interface_explicit_without_javascript · Uses: G001
S002 · implies
Before
ORIGINAL transition index=0;[from,input_or_null,required_top,to,replacement_bottom_to_top]=[push2, a2, Z2, push2, [Z2, A2]];bottom=Z2
After
states/input/stack symbols legal;null input consumes0;top=bottom requires replacement first bottom,otherwise replacement contains NO bottom;ORIGINAL transition position retained
Conditions: none
Check each original transition's state,input and stack roles without mixing alphabets.Null is epsilon,not an input symbol.The stack is bottom-first/top-last:pop one top then append the replacement in its original order.Apply the declared bottom guard,not an invented stronger convention.
Step identifiers and dependencies
Rule: pda_EVERY_original_transition_roles_epsilon_bottom_guard · Uses: G001, S001
S003 · implies
Before
ORIGINAL transition index=1;[from,input_or_null,required_top,to,replacement_bottom_to_top]=[push2, a2, A2, push2, [A2, A2]];bottom=Z2
After
states/input/stack symbols legal;null input consumes0;top=bottom requires replacement first bottom,otherwise replacement contains NO bottom;ORIGINAL transition position retained
Conditions: none
Check each original transition's state,input and stack roles without mixing alphabets.Null is epsilon,not an input symbol.The stack is bottom-first/top-last:pop one top then append the replacement in its original order.Apply the declared bottom guard,not an invented stronger convention.
Step identifiers and dependencies
Rule: pda_EVERY_original_transition_roles_epsilon_bottom_guard · Uses: G001, S002
S004 · implies
Before
ORIGINAL transition index=2;[from,input_or_null,required_top,to,replacement_bottom_to_top]=[push2, b2, A2, pop2, []];bottom=Z2
After
states/input/stack symbols legal;null input consumes0;top=bottom requires replacement first bottom,otherwise replacement contains NO bottom;ORIGINAL transition position retained
Conditions: none
Check each original transition's state,input and stack roles without mixing alphabets.Null is epsilon,not an input symbol.The stack is bottom-first/top-last:pop one top then append the replacement in its original order.Apply the declared bottom guard,not an invented stronger convention.
Step identifiers and dependencies
Rule: pda_EVERY_original_transition_roles_epsilon_bottom_guard · Uses: G001, S003
S005 · implies
Before
ORIGINAL transition index=3;[from,input_or_null,required_top,to,replacement_bottom_to_top]=[pop2, b2, A2, pop2, []];bottom=Z2
After
states/input/stack symbols legal;null input consumes0;top=bottom requires replacement first bottom,otherwise replacement contains NO bottom;ORIGINAL transition position retained
Conditions: none
Check each original transition's state,input and stack roles without mixing alphabets.Null is epsilon,not an input symbol.The stack is bottom-first/top-last:pop one top then append the replacement in its original order.Apply the declared bottom guard,not an invented stronger convention.
Step identifiers and dependencies
Rule: pda_EVERY_original_transition_roles_epsilon_bottom_guard · Uses: G001, S004
S006 · implies
Before
ORIGINAL transition index=4;[from,input_or_null,required_top,to,replacement_bottom_to_top]=[push2, null, Z2, accept2, [Z2]];bottom=Z2
After
states/input/stack symbols legal;null input consumes0;top=bottom requires replacement first bottom,otherwise replacement contains NO bottom;ORIGINAL transition position retained
Conditions: none
Check each original transition's state,input and stack roles without mixing alphabets.Null is epsilon,not an input symbol.The stack is bottom-first/top-last:pop one top then append the replacement in its original order.Apply the declared bottom guard,not an invented stronger convention.
Step identifiers and dependencies
Rule: pda_EVERY_original_transition_roles_epsilon_bottom_guard · Uses: G001, S005
S007 · implies
Before
ORIGINAL transition index=5;[from,input_or_null,required_top,to,replacement_bottom_to_top]=[pop2, null, Z2, accept2, [Z2]];bottom=Z2
After
states/input/stack symbols legal;null input consumes0;top=bottom requires replacement first bottom,otherwise replacement contains NO bottom;ORIGINAL transition position retained
Conditions: none
Check each original transition's state,input and stack roles without mixing alphabets.Null is epsilon,not an input symbol.The stack is bottom-first/top-last:pop one top then append the replacement in its original order.Apply the declared bottom guard,not an invented stronger convention.
Step identifiers and dependencies
Rule: pda_EVERY_original_transition_roles_epsilon_bottom_guard · Uses: G001, S006
S008 · calculation
Before
PDA complete ORIGINAL transition count := sum(1, 1, 1, 1, 1, 1)
After
PDA complete ORIGINAL transition count = 6
Conditions: none
Substitute original roles,order and established intermediates exactly,without changing source bindings or using floating-point approximations.
Step identifiers and dependencies
Rule: exact_rational_arithmetic · Uses: G001, S007
S009 · implies
Before
ORIGINAL states=[push2, pop2, accept2],input alphabet=[a2, b2],stack alphabet=[Z2, A2];start=push2,bottom=Z2,final states=[accept2]
After
finite unique pairwise-disjoint alphabets qualified;transition count=6;acceptance convention FULL input in final state,NOT empty stack;qualification alone proves NO run,determinism or CFG equivalence
Conditions: none
A qualified complete definition gives no accepting run,determinism or CFG-equivalence proof.Acceptance may retain a nonempty stack,including its bottom,but requires full input consumption in a final state.
Step identifiers and dependencies
Rule: pda_complete_definition_not_determinism_or_accepting_run · Uses: G001, S008
S010 · implies
Before
ORIGINAL input=[a2, a2, b2, b2];ALL source configurations=[[push2, 0, [Z2]], [push2, 1, [Z2, A2]], [push2, 2, [Z2, A2, A2]], [pop2, 3, [Z2, A2]], [pop2, 4, [Z2]], [accept2, 4, [Z2]]];declared start=push2,bottom=Z2
After
first configuration EXACTLY=[push2, 0, [Z2]];all state/position/stack values legal;this is NOT yet a valid-run or acceptance certificate
Conditions: none
Require the exact initial state,position0 and one bottom.All configurations must be structurally legal before checking their transitions.A legal configuration list alone need not be a valid run.
Step identifiers and dependencies
Rule: pda_trace_ALL_configurations_qualified_actual_initial_required · Uses: G001, S009
S011 · implies
Before
ORIGINAL trace step=0;from=[push2, 0, [Z2]];to=[push2, 1, [Z2, A2]];actual input=[a2, a2, b2, b2]
After
ALL [ORIGINAL transition index,applied_result_or_null]=[[0, [push2, 1, [Z2, A2]]], [1, null], [2, null], [3, null], [4, [accept2, 0, [Z2]]], [5, null]];FIRST matching index=0
Conditions: none
Select the first original transition that actually yields the next configuration.Input-or-null determines consumption;replace only the top and preserve replacement order.On failure retain prior partial indices;a later final state cannot repair a bad step.
Step identifiers and dependencies
Rule: pda_each_actual_stack_update_FIRST_original_transition · Uses: G001, S010
S012 · implies
Before
ORIGINAL trace step=1;from=[push2, 1, [Z2, A2]];to=[push2, 2, [Z2, A2, A2]];actual input=[a2, a2, b2, b2]
After
ALL [ORIGINAL transition index,applied_result_or_null]=[[0, null], [1, [push2, 2, [Z2, A2, A2]]], [2, null], [3, null], [4, null], [5, null]];FIRST matching index=1
Conditions: none
Select the first original transition that actually yields the next configuration.Input-or-null determines consumption;replace only the top and preserve replacement order.On failure retain prior partial indices;a later final state cannot repair a bad step.
Step identifiers and dependencies
Rule: pda_each_actual_stack_update_FIRST_original_transition · Uses: G001, S011
S013 · implies
Before
ORIGINAL trace step=2;from=[push2, 2, [Z2, A2, A2]];to=[pop2, 3, [Z2, A2]];actual input=[a2, a2, b2, b2]
After
ALL [ORIGINAL transition index,applied_result_or_null]=[[0, null], [1, null], [2, [pop2, 3, [Z2, A2]]], [3, null], [4, null], [5, null]];FIRST matching index=2
Conditions: none
Select the first original transition that actually yields the next configuration.Input-or-null determines consumption;replace only the top and preserve replacement order.On failure retain prior partial indices;a later final state cannot repair a bad step.
Step identifiers and dependencies
Rule: pda_each_actual_stack_update_FIRST_original_transition · Uses: G001, S012
S014 · implies
Before
ORIGINAL trace step=3;from=[pop2, 3, [Z2, A2]];to=[pop2, 4, [Z2]];actual input=[a2, a2, b2, b2]
After
ALL [ORIGINAL transition index,applied_result_or_null]=[[0, null], [1, null], [2, null], [3, [pop2, 4, [Z2]]], [4, null], [5, null]];FIRST matching index=3
Conditions: none
Select the first original transition that actually yields the next configuration.Input-or-null determines consumption;replace only the top and preserve replacement order.On failure retain prior partial indices;a later final state cannot repair a bad step.
Step identifiers and dependencies
Rule: pda_each_actual_stack_update_FIRST_original_transition · Uses: G001, S013
S015 · implies
Before
ORIGINAL trace step=4;from=[pop2, 4, [Z2]];to=[accept2, 4, [Z2]];actual input=[a2, a2, b2, b2]
After
ALL [ORIGINAL transition index,applied_result_or_null]=[[0, null], [1, null], [2, null], [3, null], [4, null], [5, [accept2, 4, [Z2]]]];FIRST matching index=5
Conditions: none
Select the first original transition that actually yields the next configuration.Input-or-null determines consumption;replace only the top and preserve replacement order.On failure retain prior partial indices;a later final state cannot repair a bad step.
Step identifiers and dependencies
Rule: pda_each_actual_stack_update_FIRST_original_transition · Uses: G001, S014
S016 · implies
Before
ORIGINAL last config=[accept2, 4, [Z2]];input length=4;matched prior indices=[0, 1, 2, 3, 5]
After
valid_run=Yes;FULL input consumed=Yes;last state final=Yes;accepted=Yes;residual stack may be NONEMPTY
Conditions: none
Acceptance conjoins a valid run,full input consumption and a final state.A residual bottom or other stack symbols may remain.Validity and acceptance differ;the tag cannot turn a false flag into a certificate.
Step identifiers and dependencies
Rule: pda_run_validity_full_consumption_final_state_SEPARATE · Uses: G001, S015
S017 · calculation
Before
PDA ORIGINAL full trace length minus one := sub(6, 1)
After
PDA ORIGINAL full trace length minus one = 5
Conditions: none
Substitute original roles,order and established intermediates exactly,without changing source bindings or using floating-point approximations.
Step identifiers and dependencies
Rule: exact_rational_arithmetic · Uses: G001, S016
S018 · implies
Before
ORIGINAL trace configuration count=6;actual matched transition-index count=5;accepted=Yes
After
SOURCE step_count=ORIGINAL trace.length-1=5;does NOT substitute partial matched count;acceptedTrue is a finite witness,not search completeness
Conditions: none
The source step count uses the whole supplied trace length,even on a partial failure.Only accepted=True supplies the finite accepting-run witness;it proves neither all runs,shortest length nor search completeness.
Step identifiers and dependencies
Rule: pda_original_step_count_not_partial_matched_count · Uses: G001, S017