JFLAP is pretty particular about certain things, and here are a few notes to make your life easier when testing your automata. It will also make the grader's life easier for automated testing. Starting with HW3, submissions that do not follow these guidelines may not receive full credit.
Empty String - In class and in the text, we use ε (epsilon) to denote the empty string. However, JFLAP uses λ (lambda) for this purpose. If you need a state transition (or a stack symbol for PDA's) for ε, do not enter any characters into the text box for that transition and λ will appear. Entering a space does not work; that transition will be followed only if the input string has a space on it. Similarly, entering E or "epsilon" will not work because JFLAP will try to match those exact symbols in your input string for the transition.
Multiple Transitions - If you need multiple possible inputs for the same arrow in your diagram (e.g. if you can move between states on either a 0 or a 1), this is done by creating separate edges in JFLAP for each input symbol. JFLAP will combine these into one arrow on your diagram. Do not submit automata with transitions labeled with a comma (e.g. "0,1"), because those transitions will not be followed unless "0,1" actually appears in your input string.
Regular Expressions - If asked for a regular expression, do not submit an automaton. Please don't use whitespace in your regular expressions unless a space is a valid symbol in the alphabet.
Push Down Automata - Each transition has three labels: an input symbol, a stack symbol to pop, and a stack symbol to push. JFLAP uses the semicolon (;) instead of a right arrow to separate the stack symbols. Any of the three labels can be the empty string, which is denoted by λ (see the note about the empty string). Your PDA's should be "Single Character Input" (this option appears when you first create an automaton), and they should accept by final state, not by empty stack.
Start and Accept States - Don't forget to specify these!
Context Free Grammars - If you have a production rule of the form "S -> A | B", enter it as two rules "S -> A" and "S -> B".
If you have any questions, email Alex.