  REC (REGULAR EXPRESSION COMPILER) is a programming language of simple
structure developed originally for the PDP-8 computer of the Digital Equipment,
Corporation, but readily adaptable to any other general purpose computer. It
has been used extensively in teaching Algebra and Numerical Analysis in the
Escuela Superior de F\'isica y Matem\'aticas of the Instituto Polit\'ecnico
Nacional. Moreover, the fact that the same control language, REC, is equally
applicable and equally efficient over the whole range of computer facilities
available to the students gives a very welcome coherence to the entire teaching
program, including the course of Mathematical Logic which is devoted to the
theoretical aspects of such matters.
  REC; derives its appeal from the fact that computers can be regarded
reasonably well as Turing Machines. The REC notation is simply a manner of
writing regular expression, somewhat more amenable to programming the Turing
Machine which they control. If one does not wish to think so strictly in terms
of Turing Machines, REC expressions still provide a means of defining the flow
of control in a program which is quite convenient for many applications.
