JFLAP both DFA and NFA are created using Finite Automata. . JFLAP’s home page also contains a very thorough tutorial of everything the program can do. JFLAP is written in Java to allow it to run on a range of platforms. JFLAP are going to open a JFLAP saved file of an existing finite automaton (FA). From the. Fill out the form. – 3. Download page. – 4. Get
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Note that this definition includes both deterministic finite automata DFAswhich we will be discussing shortly, and nondeterministic finite automata NFAswhich we will touch on later. That is, we will build a DFA that recognizes that language of any number of a ‘s followed by any odd number of b ‘s. This should bring up a new window that allows you to create and edit an FA. The editor is divided into two basic areas: To select a tool, click on the corresponding icon with your mouse.
When a tool is selected, it is shaded, as the Attribute Editor tool is above. Selecting the tool puts you in the corresponding mode. For instance, with the toolbar above, we are now in the Attribute Editor mode. The different modes dictate the way mouse clicks affect the machine.
For example, if we are in the State Creator mode, clicking on the canvas will create new states. These modes will be described in more detail shortly. First, let’s create several states.
Building Your First Finite Automaton
To do so we need to activate that State Creator tool by clicking the button on jfllap toolbar. Next, click on the canvas in different locations to create states. We are not very sure how many states we will need, so we created four states. Your editor window should look something like this:. Arbitrarily, we decide that q 0 will be our initial state. To define it to be our initial state, first select the Attribute Editor tool on the toolbar.
Now that we are in Attribute Editor mode, right-click on q 0. This should give us a pop-up menu that looks like this:. From the pop-up menu, select the checkbox Initial. A white arrowhead appreas to the left of q 0 to indicate that it is the inital state.
Next, let’s create a final state. Arbitrarily, we select q 1 as our final state. To define it as the final state, right-click on the state and click the checkbox Final.
It will have a double outline, indicating that it is the final state. We know strings in our language can start with a ‘s, so, the initial state must have an outgoing transition on a. We also know that it can start with any number of a ‘s, which means that the FA should be in the same state after tutoria input tutoriall any number of a ‘s.
Thus, the outgoing transition on a from q 0 loops back to itself. Tuutorial create such a transition, first select the Transition Creator tool from the toolbar. Next, click on q 0 on the canvas. A text box should appear over the state:. Preferences in the main menu to change the symbol representing the empty string. Type “a” in the text box and press Enter. If the text box isn’t selected, press Tab to yutorial it, then enter “a”. When you are done, it should look like this:.
Next, we know that strings in our language must end with a odd number of b ‘s. Thus, we tutlrial that the outgoing transtion on b from q 0 must be to a final state, as a string ending with one b should be accepted.
To create a transition from our initial state q 0 to our final state tutrial 1first ensure that the Transition Creator tool is selected on the toolbar. Next, click and hold on q 0and drag the mouse to q 1 and release the mouse button. Enter “b” in the tutoria the same way you jflao “a” for the previous transition. The transition between two states should look like this:.
Lastly, we know that only strings that end with an odd number of b ‘s should be accepted. Thus, we know that q 1 has an outgoing transition on bthat it cannot loop back to q 1. There are two options for the transtion: If the transition on b tutoial to the initial state q 0strings would not have to be of the form a m b n ; strings such as ababab would also be accepted. Thus, the transition cannot be to q 0and it must be to q 2. Create a transition on b from q 1 to q 2.
As the FA should accept strings that tutogial with an odd number of b ‘s, create another transition on b from q 2 to q 1. Your FA is now a full, working FA! It should look something like this:. You might notice that the q 3 is not used and can be deleted. Next, we will describe how to delete hflap and transitions. To delete q 3first select the Deletor tool on the toolbar.
Next, click on the state q 3. Your editor window should now look something like this:. Similarly, to delete a transition, simply click on the input symbol of the transition when in Deletor mode. Now that you’ve completed your FA, you might want to test it to see if it really accepts strings from the language. To do so, select Input: Multiple Run from the menu bar. A new tab will appear displaying the automaton on the left pane, and an input table on the right:.
To enter the input strings, click on the first row in the Input column and type in the string. Press Enter to continue to the next input string.
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When you are done, click Run Inputs to test your FA on all the input strings. The results, Accept or Reject are displayed in the Result column. You can also load the inputs from file delimited by white space. Simply click on Load Inputs and load the file to add additional input strings into multi-run pane. Clicking Clear deletes all the input tutkrial, while Enter Lambda enters the empty string at the cursor.
View Trace brings up a separate window that shows the trace of the slected input. To return to the Editor window, select File: Dismiss Tab from the menu bar. Secondly, if the FA has any transitions that read the empty string for input, it is also considered an NFA. Let’s take a look at this NFA, which can be accessed jfflap ex1. JFLAP can help with that. To see all the nondeterministic states in the NFA, select Test: Highlight Nondeterminism from the menu bar:.
We also see that q 1 is nondeterministic because two of its outgoing transitions are on the same symbol, a.
To step through input on an NFA, select Input: A dialog box prompting you for input will appear. Ordinarily, you would enter the input you wish to step through here. For now, type “aaaabb” in the dialog box and press Enter. You can also load the input file instead of typing the string. A new tab tutoeial appear displaying the automaton at the top of the window, and configurations at tuforial bottom. The current state is shaded. The configuration icon shows the current state of the configuration in the top left hand corner, and input on the white tape below.
The processed input is displayed in gray, and the unprocessed input is black. Click Step to process the next symbol of input.
You will notice q 1 becomes the shaded state in the NFA, and that the configuration icon changes, reflecting the fact that the first a has been processed.
Tuhorial Step again to process the next a. You will find that four states are shaded instead of one, and there are four configurations instead of one. This is because the machine is nondeterministic. From q 1the NFA took both a transitions to q 2 and q 9. Thus, the simulator now has four configurations. Click Step again to process the next input symbol. Notice that two of the configurations are highlighted red, indicating they were rejected.
Looking at their input, we also know that only aa was processed. To select a configuration, click on it. It will become a solid color when selected, instead of the slightly graded color. Click on the icon for the rejected configuration with state q 11and click Trace.