Gönül Aycı
Jan 11, 2018 · 6 min read

Bayesian Networks (BNs)

Figure 1: Thomas Bayes (1701–1761) [1]
Equation 1: Bayes’ Theorem [4]
  1. The percent of people overall who are rich
  1. 5% of people are rich

Figure 2: Types of probabilistic relationships [5]
Figure 3: The graphical structure of the alarm example network with probability values.
  • Image Processing,
  • Spam Filters,
  • Semantic Search *,
  • Medical Diagnosis Systems,
  • Turbo Decoding Problem [6].


Let’s create a simple Bayesian Networks with Jayes which is a Bayesian Network Library for Java [9]. Jayes is implemented by Michael Kutschke as his bachelor’s thesis.


  • You can use a software to create Bayesian networks and make an analysis. Weka is a popular data mining software in Java which has various Bayesian network classifier learning algorithms [10].
Figure 4: Sample data
Figure 5: Using Bayes Net classifier and K2 algorithm
Figure 6: The probability values of first-feature node for each behavior type of information sources
Figure 7: p(A|B).p(B) = p(A, B) = p(B|A).p(A) [12]
Figure 8: Tree diagram for events A and B [12]

Further Readings

If you are interested in this topic, I would like to recommend some resources. Bold ones are more popular than others.


  • , ” denotes AND,
  • ¬ ” denotes NEGATION operator.


Many thanks to Burak Suyunu and Yusuf Hakan Kalaycı for their reviews. This post became more understandable after their comments.


[1] Wikipedia: Thomas Bayes

Gönül Aycı

Written by

Ph.D. Candidate in CmpE @Boğaziçi University. 🏃‍♀️ 🚴‍♀️ 👩‍💻 👩‍🍳 🌳 📚 🎥 🎶

Welcome to a place where words matter. On Medium, smart voices and original ideas take center stage - with no ads in sight. Watch
Follow all the topics you care about, and we’ll deliver the best stories for you to your homepage and inbox. Explore
Get unlimited access to the best stories on Medium — and support writers while you’re at it. Just $5/month. Upgrade