ECS 120 5c:4 formal definition of TM semantics

errata:

At 4:38, I incorrectly said and wrote that L,R,S correspond to +1, -1, and 0. They correspond to -1, +1, and 0, i.e., moving left (L) decrements (-1) the tape head position, and moving right (R) increments (+1) the tape head position.