Step 1: Understanding the Interface

The simulation interface consists of four main components:

• PDA Configuration Panel: Located at the top-left, containing dropdown menus for selecting the automaton and input string
• Input Buffer Display: Shows the input string with visual highlighting of the current character being processed
• PDA Visualization: A graphical representation of the automaton with states and transitions
• Stack Display: Real-time visualization of the stack contents on the right side
• Available Transitions Panel: Shows all possible transitions from the current state

Step 2: Selecting a Pushdown Automaton

1. In the PDA Configuration section, locate the "Select PDA" dropdown menu
2. Choose from the available pushdown automata:
   • Balanced Parentheses (0^n 1^n): Accepts strings with equal numbers of 0s followed by equal numbers of 1s
   • Palindrome Checker: Accepts strings that read the same forwards and backwards
3. Read the description that appears below the dropdown to understand what language the selected PDA accepts

Step 3: Choosing an Input String

1. After selecting a PDA, use the "Select Input" dropdown menu
2. Choose from the predefined input strings designed to demonstrate both accepting and rejecting cases
3. The selected string will appear in the Input Buffer section, where each character is displayed in a separate box

Step 4: Starting the Simulation

1. Click the Start button (blue button with play icon) to begin the simulation
2. The simulation will initialize with:
   • The PDA positioned at its initial state
   • The stack containing the initial stack symbol (typically 'Z')
   • The first character of the input string highlighted in purple
   • Available transitions displayed in the right panel

Step 5: Executing Transitions

1. Observe the Available Transitions panel on the right side
2. Each transition is displayed in the format: (current_state, input_symbol, stack_top) → (next_state, stack_operation)
3. Click on any available transition to execute it
4. Watch the following changes occur:
   • The current state in the PDA diagram updates
   • The input buffer advances to the next character (if input was consumed)
   • The stack contents update based on the transition's stack operation
   • New available transitions appear for the next step

Step 6: Monitoring the Stack

1. The Stack panel shows the current contents with the top element clearly labeled
2. Stack operations are visualized in real-time:
   • Push operations: New symbols appear at the top
   • Pop operations: Top symbols are removed
   • No change: Stack remains unchanged for epsilon transitions
3. The "Top of Stack" indicator shows the current top symbol or "Z (bottom)" when only the initial symbol remains

Step 7: Tracking Input Progress

1. The Input Buffer uses color coding to show progress:
   • Purple highlighting: Current character being processed
   • Green background: Characters already processed
   • Gray background: Characters yet to be processed
2. Some transitions consume input (advance the pointer), while others are epsilon transitions (no input consumption)

Step 8: Understanding Acceptance and Rejection

1. Successful Acceptance: The simulation succeeds when:

   • All input characters have been consumed (input buffer fully processed)
   • The automaton reaches an accepting state
   • The stack may or may not be empty (depending on acceptance criteria)

2. Rejection: The simulation fails when:

   • No valid transitions are available from the current configuration
   • The input is fully consumed but the automaton is not in an accepting state

Step 9: Using Control Features

1. Step Back: Click the "Step Back" button (purple) to undo the last transition and return to the previous configuration
2. Reset: Click the "Reset" button (red) to return to the initial state and restart the simulation
3. Try Different Inputs: Use the reset function to experiment with different input strings on the same PDA

Step 10: Experimenting and Learning

1. Try both accepting and rejecting strings to understand the difference
2. Pay attention to how the stack is used to remember information
3. Notice how different transitions become available based on the current state, input character, and stack top
4. Experiment with the step-back feature to explore alternative execution paths