enter a loop when printing individual name when reason is enabled.

With reasoner enabled, the generator self.world.individuals() will enter a loop after printing the first individual. The code snippet is shown below:
---> 33         for each_global_individual in self.world.individuals():
     34             print(each_global_individual.name)

Output is shown below (the system hang after print the first individual name)
individuals are as below:
CapitalCity

The reasoner is enabled by the following code.
sync_reasoner_pellet(self.world, infer_property_values=True, infer_data_property_values=True)

When I commented out the above reasoner line, it worked fine.

When I hit ctrl C, it will print the following exception:
Traceback (most recent call last):
  File "/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.9/site-packages/owlready2/namespace.py", line 638, in _get_by_storid
    return self._load_by_storid(storid, full_iri, main_type, main_onto, default_to_none)
  File "/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.9/site-packages/owlready2/namespace.py", line 643, in _load_by_storid
    with LOADING:
  File "/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.9/site-packages/owlready2/util.py", line 298, in __enter__
    def __enter__(self): self.level.set(self.level.get() + 1)
RecursionError: maximum recursion depth exceeded while calling a Python object

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.9/site-packages/owlready2/namespace.py", line 638, in _get_by_storid
    return self._load_by_storid(storid, full_iri, main_type, main_onto, default_to_none)
  File "/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.9/site-packages/owlready2/namespace.py", line 760, in _load_by_storid


Thanks for your time looking into my issue. When I get familiar with this project, should check out the source code to see whether I can debug it.

[Jiba]

Hello,

Can you send me your ontology, for reproducing the problem please?

Best regards,
Jiba

I tried the button clicks "More > Upload a file > Choose File > Upload file" and it doesn't work.

Hence, I uploaded to my web site. Here is link http://vehorg.com/external/owlready_question.zip. Feel free to download my ontology file for debugging.

The following is my code snippet to reproduce the problem:

from owlready2 import *

if __name__ == "__main__":
    onto_file = "/home/ernest/Downloads/bespoke_travel_ontology.owl"
    prefix = "http://www.vehorg.com/2024/04/bespoke_travel#"
    world = World()
    world.get_ontology(onto_file).load()
    # avoid duplicated ontology
    # self.world.set_backend()  # owlready2 will automatically update quadstore.
    # use inference engine
    sync_reasoner_pellet(
        world, infer_property_values=True, infer_data_property_values=True
    )
    for each_global_individual in world.individuals():
        print(each_global_individual.name)
    print("=" * 60)

Are you able to reproduce m problem? Just checking.

[Jiba]

Yes, I finally found the problem: it was caused by an individual belonging to several classes with one of these classes having a OneOf construct including that individual. This creates a kind of cycle, thus leading to an infinite loop.

I have fixed the problem in the development version of Owlready on Bitbucket, and I was able to run your example successfully with the fix!

Jiba

Great! I am building a model driven knowledge graph for my LLM. Hence, an instance may belong to multiple classes.

When my level 4 conversation AI is up, I will use the SPARQL of owlready2 to answer questions. Thanks again. I love owlready2.

Just downloaded the latest version: Successfully installed owlready2-0.46.

It is getting better which past the previous failure. However, there is a new error message as shown below:
* Owlready2 * Running Pellet...
    java -Xmx2000M -cp /home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.10/site-packages/owlready2/pellet/jena-tdb-0.10.0.jar:/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.10/site-packages/owlready2/pellet/httpclient-4.2.3.jar:/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.10/site-packages/owlready2/pellet/antlr-runtime-3.2.jar:/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.10/site-packages/owlready2/pellet/pellet-2.3.1.jar:/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.10/site-packages/owlready2/pellet/commons-codec-1.6.jar:/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.10/site-packages/owlready2/pellet/owlapi-distribution-3.4.3-bin.jar:/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.10/site-packages/owlready2/pellet/slf4j-api-1.6.4.jar:/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.10/site-packages/owlready2/pellet/jcl-over-slf4j-1.6.4.jar:/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.10/site-packages/owlready2/pellet/aterm-java-1.6.jar:/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.10/site-packages/owlready2/pellet/log4j-core-2.19.0.jar:/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.10/site-packages/owlready2/pellet/xml-apis-1.4.01.jar:/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.10/site-packages/owlready2/pellet/log4j-api-2.19.0.jar:/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.10/site-packages/owlready2/pellet/antlr-3.2.jar:/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.10/site-packages/owlready2/pellet/slf4j-log4j12-1.6.4.jar:/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.10/site-packages/owlready2/pellet/jena-arq-2.10.0.jar:/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.10/site-packages/owlready2/pellet/log4j-1.2-api-2.19.0.jar:/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.10/site-packages/owlready2/pellet/xercesImpl-2.10.0.jar:/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.10/site-packages/owlready2/pellet/jena-core-2.10.0.jar:/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.10/site-packages/owlready2/pellet/httpcore-4.2.2.jar:/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.10/site-packages/owlready2/pellet/jena-iri-0.9.5.jar:/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.10/site-packages/owlready2/pellet/jgrapht-jdk1.5.jar pellet.Pellet realize --loader Jena --input-format N-Triples --infer-prop-values --infer-data-prop-values --ignore-imports /tmp/tmp2h20k1yy
* Owlready2 * Pellet took 8.639118194580078 seconds
* Owlready * (NB: only changes on entities loaded in Python are shown, other changes are done but not listed)
bespoke_travel_ontology.BestDeal
bespoke_travel_ontology.CostEstimation
bespoke_travel_ontology.CruiseFinder
bespoke_travel_ontology.LowBudgetFinder
bespoke_travel_ontology.TicketFinder
bespoke_travel_ontology.CapitalCity
bespoke_travel_ontology.MajorCity
bespoke_travel_ontology.SmallCity
bespoke_travel_ontology.BigFamily
bespoke_travel_ontology.CompanyEventTravel
bespoke_travel_ontology.CompanyGroupTravel
bespoke_travel_ontology.CompanySoloTravel
bespoke_travel_ontology.FamilyWithKid
bespoke_travel_ontology.ReligiousTravel
bespoke_travel_ontology.RetiredCouple
bespoke_travel_ontology.Solo
bespoke_travel_ontology.SportTeamTravel
bespoke_travel_ontology.TravelEntourage
bespoke_travel_ontology.YoungCouple
bespoke_travel_ontology.Summer
bespoke_travel_ontology.Winter
bespoke_travel_ontology.BoutiqueHotel
bespoke_travel_ontology.BudgetHotel
bespoke_travel_ontology.ChainHotel
bespoke_travel_ontology.LuxuryHotel
bespoke_travel_ontology.DomesticTravel
bespoke_travel_ontology.InternationalTravel
bespoke_travel_ontology.Sport
bespoke_travel_ontology.Fall
bespoke_travel_ontology.Spring
bespoke_travel_ontology.AirTravel
bespoke_travel_ontology.RailTravel
bespoke_travel_ontology.RoadTravel
bespoke_travel_ontology.WaterTravel
bespoke_travel_ontology.Countryside
bespoke_travel_ontology.FarmStay
bespoke_travel_ontology.Ranch
bespoke_travel_ontology.CoastalTown
bespoke_travel_ontology.MountainTown
bespoke_travel_ontology.TouristTown
bespoke_travel_ontology.BrickAndMortar
bespoke_travel_ontology.Online
bespoke_travel_ontology.TravelOperator
bespoke_travel_ontology.CustomizedDailyHouseKeeping
bespoke_travel_ontology.CustomizedGroceryDelivery
bespoke_travel_ontology.CustomizedMarketingMaterialsWithPhoto
bespoke_travel_ontology.CustomizedReview
bespoke_travel_ontology.Consistency
bespoke_travel_ontology.Flexibility
bespoke_travel_ontology.Privacy
bespoke_travel_ontology.Service
bespoke_travel_ontology.Space
bespoke_travel_ontology.Value
bespoke_travel_ontology.DemographicPreference
bespoke_travel_ontology.ForeignCountryRestriction
bespoke_travel_ontology.LocalStateOrCityRestriction
bespoke_travel_ontology.LocalTrend
bespoke_travel_ontology.LocationRestriction
bespoke_travel_ontology.WeatherRestriction
bespoke_travel_ontology.Arrival
bespoke_travel_ontology.Departure
bespoke_travel_ontology.Apartment
bespoke_travel_ontology.BeachResort
bespoke_travel_ontology.Cabin
bespoke_travel_ontology.Condo
bespoke_travel_ontology.GolfResort
bespoke_travel_ontology.House
bespoke_travel_ontology.Villa
Traceback (most recent call last):
  File "/home/ernest/nomadic_bot/test_bug.py", line 14, in <module>
    for each_global_individual in world.individuals():
  File "/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.10/site-packages/owlready2/namespace.py", line 245, in individuals
    i = self.world._get_by_storid(s)
  File "/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.10/site-packages/owlready2/namespace.py", line 645, in _get_by_storid
    return self._load_by_storid(storid, full_iri, main_type, main_onto, default_to_none)
  File "/home/ernest/miniconda3/envs/nomadicbotenv/lib/python3.10/site-packages/owlready2/namespace.py", line 768, in _load_by_storid
    elif len(types) >  1: entity = FusionClass._get_fusion_class(types)(name = name, namespace = namespace, is_a = types)
TypeError: FusionClass1() takes no arguments

Today, I tried a few SPARQL query. If the relationship is too generic, I will bumped into this problem. It seems that this bug will surface in a number of different way.

When I get to the point which I need to fix all these issue, will download the open source and try to debug it.

It is confirmed that it is due to that some of my instances have equivalent classes and has abstract class.

Thanks for your work of owlready2. It is wonderful because I can use it for the 1st release of our Digital Travel Agent. I think my main issue is that I have too many fine grained classes and object properties. You can easily know that I am a newbie to the implementation of Ontology.

After giving a deep 2nd thought, I think I will consolidate fine-grained relationship as I can ask the type of object to know more. It seems that generic predicate will not be welcome for SPARQL.

That means I will not bump into this issue so often now as I will deal with a lot of concrete relationship and classes.

In case I am blocked by this issue in the future, will definitely download the source code and try to fix it.

Lastly but not lease, thanks a million to your help. Have a good day.

My further investigation showed that the main issue is due to the Enum in my Ontology. Don't do it because it will cause severe performance degradation and infinite loop in owlready2.

The Enum means that I create a class with EquivalentTo all the instances {BestDeal, CostEstimation}. As the old saying said, the C Enum is a devil to performance.