L1L2
Definition: Let L1 and L2 be two languages over S. The concatenation of L1 and L2, L1L2 , is defined as
L1L2 = {xy: x Î L1 and y Î L2}
Note: 1) L{e}= {e}L = L 2) LÆ = ÆL = Æ
00
0
01
0
00
1
01
1
L1
0
1
L2
00
01
Example: Consider languages L1= {0, 1}, L2= {00, 01}
Task:  L1L2
Concatenation of Languages
Gist: L1L2 = {xy: x Î L1 and y Î L2}
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