Given two languages L1 , L2 7*, we define L1hL2= [uhv | u # L1 , v # L2]. The well-known operations of catenation, right left quotient and shuffle product are examples of such operations. Other examples include the insertion and deletion operations. Recall that (see [3, 4]) given words u, v # 7*, the insertion of v into u is u v= [u1vu2 | u=u1u2] and the deletion of v from u is defined as u v=[...
