Regular Expression Input Window

Regular Expression Input Window
To convert from a Regular Expression to a FSA, one must first input the Regular Expression into the Regular Expression Input Window. Then press "Create FSA" to begin creating the Automata.

NOTE: Lambda transitions can be inputted by entering the "!" character.

The Conversion Algorithm
Converting from a Regular Expression to a FSA involves a specific algorithm. The conversion involves the presentation of each part of the Regular Expression inputted until the entire Regular Expression has been constructed.

In order to construct the FSA, the algorithm follows several rules which the user must also conform to in order to allow the checking procedure to work correctly. The rules used by the algorithm may have extraneous parts in some cases, but they are necessary in specific instances. Thus, the algorithm will produce a non-minimal, but correct, FSA.

The following are the rules that the Regular Expression and the user must follow:

Building the FSA from the Regular Expression
Once the Regular Expression has been inputted and the Create FSA button is pressed, a new FSA window appears for the creation of the FSA. In the main toolbar, the message "Create the Regular Expression: " followed by a Regular Expression to create is displayed. This Regular Expression tells what subexpression of the Regular Expression that was inputted should be made at the present step. The idea is to gradually build the finished FSA from the ground up. Automatically, the starter FSAs for each variable used in the conversion are added to the FSA window. Thus, what the user needs to do is to connect up the starter FSAs in the method described above (possibly adding new states if necessary).

Under the Solve menu, there are several options:

Before one can continue on to the next step of this conversion, it is required that the current step is correct. As a result, selecting Next Step when the current Regular Expression has not been finished will not work.