Difference between revisions of "Theoretical Aspects of Lexical Analysis/Exercise 2"

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< Theoretical Aspects of Lexical Analysis
(DFA)
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* <nowiki>(a*|b*)*</nowiki>
 
* <nowiki>(a*|b*)*</nowiki>
  
== Solution ==
+
== NFA ==
 
 
=== NFA ===
 
  
 
The following is the result of applying Thompson's algorithm.
 
The following is the result of applying Thompson's algorithm.
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</graph>
 
</graph>
  
=== DFA ===
+
== DFA ==
  
 
Determination table for the above NFA:
 
Determination table for the above NFA:

Revision as of 06:05, 22 March 2009

Use Thompson's algorithm to build the NFA for the following regular expression. Build the corresponding DFA and minimize it.

  • (a*|b*)*

NFA

The following is the result of applying Thompson's algorithm.


DFA

Determination table for the above NFA:

In α∈Σ move(In, α) ε-closure(move(In, α)) In+1 = ε-closure(move(In, α))
- - 0 0, 1, 2, 3, 5, 6, 7, 9, 10, 11 0
0 a 4 1, 2, 3, 4, 5, 6, 7, 9, 10, 11 1
0 b 8 1, 2, 3, 5, 6, 7, 8, 9, 10, 11 2
1 a 4 1, 2, 3, 4, 5, 6, 7, 9, 10, 11 1
1 b 8 1, 2, 3, 5, 6, 7, 8, 9, 10, 11 2
2 a 4 1, 2, 3, 4, 5, 6, 7, 9, 10, 11 1
2 b 8 1, 2, 3, 5, 6, 7, 8, 9, 10, 11 2


Graphically, the DFA is represented as follows:


Given the minimization tree to the right, the final minimal DFA is:


The minimization tree is as follows. As can be seen, the states are indistinguishable.