Is there a mutation probability in tutorial 4?
in koza.params it says:

# Point Mutation will use Tournament Selection, try only 1
# time, have a max depth of 17, and use KozaNodeSelector
# and GROW for building.  Also, Point Mutation uses a GrowBuilder
# by default, with a default of min-depth=max-depth=5
# as shown a ways below
gp.koza.mutate.source.0 = ec.select.TournamentSelection
gp.koza.mutate.ns.0 = ec.gp.koza.KozaNodeSelector
gp.koza.mutate.build.0 = ec.gp.koza.GrowBuilder
gp.koza.mutate.maxdepth = 17
# This is the default for Koza and lil-gp, though it's
# a little wimpy; on the other hand, a higher number can
# make things really slow
gp.koza.mutate.tries = 1

But i don't see any probability for that mutation.

kind regards