TCT: A Computation Tool for Supervisory Control Synthesis. The TCT software package is designed for the synthesis of supervisory controls for untimed discrete-event systems (DES). It can be downloaded from [6], where two different programs are posted for untimed DES: XPTCT , previously known as CTCT , for Windows 95/98/2000/XP and LTCT for Linux systems. The two programs implement exactly the same algorithms, but on different platforms.