Concatination property of DFAs

In this property we say that concatination of two DFAs are also a DFA

We will explain union using one example, (we already have explained the below DFA)

So as you see in the above picture, we have taken two DFAs
  1. Starts with 'a'
  2. Ends with 'b'
Languages represented by them are respectively
  1. L1 = {a, aa, ab, aaa, abbb, ... }
  2. L2 = {b, ab, abb, bb, aab, ... }

After taking concatination new language became "Starting with 'a' and ending with 'b'
As, L = {ab, aab, abb, aaab, ...}
Note: clearly the language is infinite
You can also take some examples from the previous exercises for practice.