Given a string encoder that encoder plaint text to code we want to generate its inversion, a decoder, that decode the code into the original plain text correctly. In fact, when an encoder is given as a program it is hard to invert it. However using transducers to represent a string encoder make the inversion much more promising. In this seminar, the definition of ESFT will be first introduced and then we will discuss about how to determine an Extended Symbolic Finite Transducer, how to determine the output language of an Extended Symbolic Finite Transducers and how to invert an transducer.
This is preliminary work with Loris D'Antoni.