As Stephane also pointed out earlier, if you want to create a number of randomised solutions, but then later want to fix the result to one solution/seed of your choice, one way to do that is to always print the current seed, and in the end to simply replace your randomly generated seed with a seed of your choice.  (progn  (setf seed (random 1000))   (print seed) ;; replace seed below ultimately with seed generating a result you like (init-seed seed)) Best, Torsten