Problem 11
A Turing machine with doubly infinite tape is similar to an ordinary
Turing machine except that its tape is infinite to the left as well as
to the right. The tape is initially filled with blanks except for the
portion that contains the input. Computation is defined as usual except
that the head never encounters an end to the tape as it moves leftward.
Show that this type of Turing machine recognizes the class of
Truing-recognizable languages.
