add config options for narrow deep paths mutation

Author: nandikaK

config/defaults.py

@@ -78,6 +78,9 @@
 MUTPB_FV_SAMPLE_MAXN = 32  # max n of instantiations to sample from top k
 MUTPB_FV_QUERY_LIMIT = 256  # SPARQL query limit for the top k instantiations
 MUTPB_SP = 0.05  # prob to simplify pattern (warning: can restrict exploration)
-
+MUTPB_DN = 0.05  # prob to try a deep and narrow paths mutation
+MUTPB_DN_MIN_LEN = 2  # minimum length of the deep and narrow paths
+MUTPB_DN_MAX_LEN = 10  # absolute max of path length if not stopped by term_pb
+MUTPB_DN_TERM_PB = 0.3  # prob to terminate node expansion each step > min_len
 # for import in helpers and __init__
 __all__ = [_v for _v in globals().keys() if _v.isupper()]