-Alan turing. -Language: Recursively Enumerable Language -Unrestricted Grammar (Why because there is no restriction for data reading .... Read data from Either Left or right side) - Input Tape: ----------- B B <string divided and keep in each cells> B B --------------- Finite Control Use "Tape head" to read at a time one letter from input-tape cell. - Formal Definition M=(Q,Sigma,Toe,Delta,q0,B,F) // 7 tuples or 7 elements...that we need to develop a TM Delta maps from Delta: Q X Toe -> Q X Toe X {L,R,S} Movements are L(Left),R(Right),S(Stationary)