Original question and givens
Use the complete finite nondeterministic PDA: states=[push20, pop20, accept20], input_alphabet=[a20, b20], stack_alphabet=[Z20, A20], start_state=push20, bottom_symbol=Z20, final_states=[accept20], transitions=[[push20, a20, Z20, push20, [Z20, A20]], [push20, a20, A20, push20, [A20, A20]], [push20, b20, A20, pop20, []], [pop20, b20, A20, pop20, []], [push20, null, Z20, accept20, [Z20]], [pop20, null, Z20, accept20, [Z20]]]. 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=[], supplied trace=[[push20, 0, [Z20]], [accept20, 0, [Z20]]]. Give (input, trace, transition_indices, valid_run, accepted, step_count, certificate).
G001 — Use the complete finite nondeterministic PDA: states=[push20, pop20, accept20], input_alphabet=[a20, b20], stack_alphabet=[Z20, A20], start_state=push20, bottom_symbol=Z20, final_states=[accept20], transitions=[[push20, a20, Z20, push20, [Z20, A20]], [push20, a20, A20, push20, [A20, A20]], [push20, b20, A20, pop20, []], [pop20, b20, A20, pop20, []], [push20, null, Z20, accept20, [Z20]], [pop20, null, Z20, accept20, [Z20]]]. 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=[], supplied trace=[[push20, 0, [Z20]], [accept20, 0, [Z20]]]. 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]=[push20, a20, Z20, push20, [Z20, A20]];bottom=Z20
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]=[push20, a20, A20, push20, [A20, A20]];bottom=Z20
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]=[push20, b20, A20, pop20, []];bottom=Z20
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]=[pop20, b20, A20, pop20, []];bottom=Z20
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]=[push20, null, Z20, accept20, [Z20]];bottom=Z20
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]=[pop20, null, Z20, accept20, [Z20]];bottom=Z20
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=[push20, pop20, accept20],input alphabet=[a20, b20],stack alphabet=[Z20, A20];start=push20,bottom=Z20,final states=[accept20]
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=[];ALL source configurations=[[push20, 0, [Z20]], [accept20, 0, [Z20]]];declared start=push20,bottom=Z20
After
first configuration EXACTLY=[push20, 0, [Z20]];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=[push20, 0, [Z20]];to=[accept20, 0, [Z20]];actual input=[]
After
ALL [ORIGINAL transition index,applied_result_or_null]=[[0, null], [1, null], [2, null], [3, null], [4, [accept20, 0, [Z20]]], [5, null]];FIRST matching index=4
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 last config=[accept20, 0, [Z20]];input length=0;matched prior indices=[4]
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, S011
S013 · calculation
Before
PDA ORIGINAL full trace length minus one := sub(2, 1)
After
PDA ORIGINAL full trace length minus one = 1
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, S012
S014 · implies
Before
ORIGINAL trace configuration count=2;actual matched transition-index count=1;accepted=Yes
After
SOURCE step_count=ORIGINAL trace.length-1=1;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, S013