Probabilistic logic programs are logic programs in which some of the facts are annotated with probabilities.

ProbLog is a tool that allows you to intuitively build programs that do not only encode complex interactions between a large sets of heterogenous components but also the inherent uncertainties that are present in real-life situations.

The engine tackles several tasks such as computing the marginals given evidence and learning from (partial) interpretations. ProbLog is a suite of efficient algorithms for various inference tasks. It is based on a conversion of the program and the queries and evidence to a weighted Boolean formula. This allows us to reduce the inference tasks to well-studied tasks such as weighted model counting, which can be solved using state-of-the-art methods known from the graphical model and knowledge compilation literature.

The Language. Probabilistic Logic Programming.

ProbLog makes it easy to express complex, probabilistic models.

0.3::stress(X) :- person(X).
0.2::influences(X,Y) :- person(X), person(Y).

smokes(X) :- stress(X).
smokes(X) :- friend(X,Y), influences(Y,X), smokes(Y).

0.4::asthma(X) :- smokes(X).



Get to know the language using our interactive tutorial, check out our publications or try the above example directly in our online editor.

For an introduction, please consult the following papers

The Engine. Powerful inference.

ProbLog2 is our 2nd generation engine to reason with the ProbLog language. The current engine builds on logic programming, knowledge compilation, the distribution semantics and probabilistic, graphical models. It allows you to:

For more information about these inference and learning tasks and how they are solved in ProbLog2, please consult the following papers.



Online interface. No hassle.

You can try out ProbLog using our online editor.

Try tutorial  Try inference and learning 

Download. Use, change, improve.

ProbLog2 binaries and source are available for download. The only requirement is Python 2.7/3. ProbLog2 is licensed under the GPL3 license (contact us for alternative licenses).

Download latest version

ProbLog2 can optionally make use of: SDDs, c2d and YAP Prolog.
The previous version of ProbLog (ProbLog1) is available as part of YAP Prolog or can be downloaded from the old Problog1 webpages

Need help? Fire any question or report a bug to our team.

Mailing list

There is a general ProbLog mailing list which you can use for all your ProbLog1 and ProbLog2 questions or bug reports. You can also consult the mailing list archive to see if your question has been asked before.

The ProbLog team.

ProbLog2 was developed in the DTAI group of KULeuven, by the following people (in alphabetical order).

Other people who contributed to ProbLog1 and 2 (in alphabetical order):

Our colleagues from the probabilistic programming community.