FLAP

NOTE: This page is very old. See www.jflap.org for the most recent version of this tool.

FLAP (Formal Languages and Automata Package), a tool for designing, and simulating several variations of finite automata, pushdown automata, and Turing machines. Using FLAP, one can draw a picture (transition diagram) of a nondeterministic automaton. Once the picture is complete, the user enters an input string and then controls a step-by-step simulation showing multiple stacks, one for each possible configuration. Additional features of FLAP include a fast simulation mode, and retracing part or all of a simulation. FLAP is currently used worldwide in teaching automata theory.

FLAP was been worked on by many people: Susan H. Rodger, Dan Caugherty, Mark LoSacco, David Harrison, and Greg Badros.

FLAP and other tools are available via anonymous ftp to ftp.cs.duke.edu in the directory pub/rodger/tools.

Pictures of automata constructed using FLAP

Finite Automata
- Strings formed over {a,b} that contain an even number of a's and an even number of b's
- Example of nondeterministic finite automaton
Pushdown Automata
Turing Machines
- Add two unary numbers. For example, 111+11=11111
- Double a string of a's. For example, input: aaa, output: aaaaaa
2-tape Turing Machines
- L={a^nb^nc^n | n>0}

Example of DETERMINISTIC trace of adding two unary numbers in Turing machine above.

Initial starting configuration
1 step later
final configuration

Examples of a NONDETERMINISTIC trace for palindrome Pushdown automaton above.

Initial starting configuration
1 step later
1 step later shows 2 possible configurations
1 step later shows 3 possible configurations
final configuration

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