Savitch W.J., Vitányi P.M.B. (1977) Linear time simulation of multihead turing machines with head — To-head jumps. In: Salomaa A., Steinby M. (eds) Automata, Languages and Programming. ICALP 1977. Lecture Notes in Computer Science, vol 52. Springer, Berlin, Heidelberg
The main result of this paper shows that, given a Turing machine with several read-write heads per tape and which has the additional one move shift operation "shift a given head to the position of some other given head", one can effectively construct a multitape Turing machine with a single read-write head per tape which simulates it in linear time; i.e. if the original machine operates in time T(n), then the simulating machine will operate in time cT(n), for some constant c.