Seminar of Computer Networks: Online Social Networks and Network Economics

Academic Year 2009 / 2010

Online social networks have become a major driving phenomena on the web since the Internet has expanded as to include users and their social systems in its description and operation. Internet has developed from a communication medium and information sharing devise into a platform enabling a wide range of new social activities and applications. There is a growing number of highly-popular user-centric applications in Internet that rely on social networks for mining and filtering information, for providing recommendations, tags, annotations, as well as for ranking of documents and services. Successfully striking examples are collaborative recommendation systems (e.g., Amazon for books and Netflix for DVDs), folksonomies - systems of collaborative social tagging - (e.g., Citeulike, Delicious, Flickr and Youtube), cooperative systems for building repositories of information as Wikipedia, systems of social networking (e.g., myspace, Facebook) and forum of discussion and opinion formation (e.g., blogs and Web communities). In this course we will present the design principles and the main structural properties and theoretical models of on-line social networks, algorithms for data mining in social networks, and some network economic issues.


1/7/2010: The solutions for the second homework are out.

20/6/2010: From 22/6 Aris will be out of Rome with limited access to email. For questions mail to Ilaria or to Stefano Leonardi.

18/6/2010: There is a disagreement between the due date of homework 2 in the web page and in the homework. Thus, we move the due date to June 30. You can email the homework to Stefano Leonardi.

1/6/2010: The second homework is out, due June 30. Same instructions as the first one.

6/5/2010: You can find the directions and some ideas about the final projects here. In the final exam you will have to present your final project and to talk about your mistakes in the homeworks. For questions send an email to Aris or Ilaria.

6/5/2010: The solutions for the first homework are out. You should study them for the final exam. If you have any questions or if you find any mistakes please send an email to Aris.

29/4/2010: If you're searching for a partner for the final project send an email to Aris to try to match you.

30/3/2010: The first homework is out, due April 28, before class. Read carefully the instructions.


Prof. Stefano Lenardi, Sapienza University of Rome
Dr. Aris Anagnostopoulos, Sapienza University of Rome, email:
Ilaria Bordino, Sapienza University of Rome

When and Where

When: Wednesday 14.00-15.30 and 16.00-17.30
Where: Via Ariosto 25, Aula

Office Hours

Aris: Monday, 2pm-3pm, office B118. If you have classes at this time we can arrange by email.


There does not exist a book for the class material. We will post the slides and maybe some notes for some of the lectures.


We will cover some of the following topics, and maybe a few more to be decided:

Homeworks, Exams

We will have 2 homework sets and a final project.

Homework 1 (due April 28, before class)
Solutions for Homework 1.
Homework 2 (due June 30)
Solutions for Homework 2.
Instructions for the final project.


Class notes (last updated 14/3/2010)

4/3/2010: Basic combinatorics
Basic matirial for counting permutations and combinations, binomial coefficients, etc.

4/3/2010: Introduction to probability
Here you can find a brief introduction to probability. Make sure that you understand all the material.

4/3/2010: Random variables
This describes random variable, expectation, variance, and other related topics. We will work mostly with discrete random variables but you should know the basics for the continuous ones.

4/3/2010: Main distribution functions
It describes the main types of distributions. Definitely understand Section 5.1 and you can study the rest when we do them in the class


Make sure that you read also the lecture notes for the material we covered and is not in the slides (networks models, etc.).

4/3/2010: Introduction, 3/3/2010: Introduction, structural properties, Erdos-Renyi random-graph model

14/3/2010: Probability, 10/3/2010: Basic discrete probability, random variables, expectation

25/3/2010: Epidemics and Models for Contagion, 17/3/2010:

25/3/2010: Influence Maximization, 24/3/2010

25/3/2010: Influence and Correlation, 24/3/2010

25/3/2010: Introduction to Community Detection, 24/3/2010

9/4/2010: Social Tagging Systems, 7/4/2010

21/4/2010: Query Logs, 14/4/2010

29/4/2010: Introduction to Computational Advertising (slides from Stanford), 28/4/2010

1/6/2010: Marketplace and Economics (slides from Stanford)

1/6/2010: Sponsored Search (slides from Stanford)

29/4/2010: A Crash Course in Information Retrieval (slides from Stanford), 28/4/2010