  DCSYNTH is a tool for the synthesis of controllers from safety and bounded
liveness requirements given in interval temporal logic QDDC. It investigates
the role of soft requirements (with priorities) in obtaining high quality
controllers. A QDDC formula specifies past time properties. In DCSYNTH
synthesis, hard requirements must be invariantly satisfied whereas soft
requirements may be satisfied "as much as possible" in a best effort manner by
the controller. Soft requirements provide an invaluable ability to guide the
controller synthesis. In the paper, using DCSYNTH, we show the application of
soft requirements in obtaining robust controllers with various specifiable
notions of robustness. We also show the use of soft requirements to specify and
synthesize efficient runtime enforcement shields which can correct burst
errors. Finally, we discuss the use of soft requirements in improving the
latency of controlled system.
