sentences:  In the current ALF implementation programs of this abstract machine are executed by an emulator written in C.
  
  In the Carnegie Mellon University Artificial Intelligence Repository, ALF is included as an AI programming language, in particular as a functional/logic programming language Prolog implementation.A user manual describing the language and the use of the system is available.The ALF System runs under Unix and is available under a custom proprietary software license that grants the right to use for "evaluation, research and teaching purposes" but not commercial or military use.