Be able to construct PDAs to recognize specific languages
A Nondeterministic Pushdown Automata is similar to a FA but with
additional memory in the form of a stack. Symbols can be pushed onto and
popped off of the stack. A transition must now encode two inputs ( what must
be read from input and the top of the stack before you can take this
transition) and one output (what must be pushed onto the stack if you decide
to take this transition). A transition for a PDA is defined in JFLAP as
W,X;Y where W represents the input symbols to be processed, X represents the
stack symbols that must be on the stack and are popped off the stack, and Y
represents the stack symbols that are pushed onto the stack. Note the
comma separates the two inputs (what must be matched if this transition is
to be taken) and the semicolon separates the inputs from the output.
We also use the special symbol "Z" to denote the empty stack symbol.
Download the lab8 files and start JFLAP 6.0. Open file file ex8.1 in
the Pushdown Automata editor.
Try Step with Closure with the input abb. Does it accept?
Try Step with Closure again with the input aabb. Does it accept?
Clearly and succinctly describe the language that is accepted by
the PDA in ex8.1
Build and thoroughly test PDAs for the exercises 4c,k on p183 of
your text.