As any first-order prover is wont to do, Snark is likely to either loop forever or run for a longer time than the user can wait. The user can provide a time limit for Snark by using an appropriate option. However, there are likely to be times when the user wants to stop Snark in the middle of execution. The user can do this by typing Cntrl-C Cntrl-C in the *common-lisp* buffer. This will then interrupt Snark and place the user in the Lisp debugger. The user can exit the debugger by issuing the :pop command. A log file will still be written that can be perused if so desired.