Union, Theory of Computation

Intuitively, closure of SL2 under intersection is reasonably easy to see, particularly if one considers the Myhill graphs of the automata. Any path through both graphs will be a path through the intersection of the graphs (by which we mean the graph resulting by taking the intersection of the vertex sets and the intersection of the edge sets).

For the union, on the other hand, the corresponding construction won't work. An automaton built from the union of the two automata will still recognize all of the strings in L1 and all of the strings in L2, but it is likely to also recognize strings made up of adjacent pairs from L1 combined with adjacent pairs from L2 that aren't in either language. And, in fact, we can use Suffx Substitution Closure to show that there are languages that are the union of two SL2 languages that are not, themselves, SL2.

Posted Date: 3/22/2013 12:49:44 AM | Location : United States







Related Discussions:- Union, Assignment Help, Ask Question on Union, Get Answer, Expert's Help, Union Discussions

Write discussion on Union
Your posts are moderated
Related Questions
examples of decidable problems


If the first three words are the boys down,what are the last three words??

proof ogdens lemma .with example i am not able to undestand the meaning of distinguished position .

Trees and Graphs Overview: The problems for this assignment should be written up in a Mircosoft Word document. A scanned hand written file for the diagrams is also fine. Be

Lemma 1 A string w ∈ Σ* is accepted by an LTk automaton iff w is the concatenation of the symbols labeling the edges of a path through the LTk transition graph of A from h?, ∅i to

When we say "solved algorithmically" we are not asking about a speci?c programming language, in fact one of the theorems in computability is that essentially all reasonable program

Ask queyystion #Minimum 100 words accepted#

Automaton (NFA) (with ε-transitions) is a 5-tuple: (Q,Σ, δ, q 0 , F i where Q, Σ, q 0 and F are as in a DFA and T ⊆ Q × Q × (Σ ∪ {ε}). We must also modify the de?nitions of th

De?nition (Instantaneous Description) (for both DFAs and NFAs) An instantaneous description of A = (Q,Σ, δ, q 0 , F) , either a DFA or an NFA, is a pair h q ,w i ∈ Q×Σ*, where