Summary: A Serendipity-Oriented Greedy Algorithm for Recommendations

Full text available: proceedings | direct link.

Denis Kotkov, Jari Veijalainen, and Shuaiqiang Wang. 2017. A Serendipity- Oriented Greedy Algorithm for Recommendations. In Proceedings of the 13th International Conference on Web Information Systems and Technologies, Vol. 1. ScitePress, 32–40.

Installing Flask on Windows

Here is a quick instruction:

Angular simple routing example

Let's create a new project:

Analysis of algorithms

Let T(n) be a function on n=1,2,3...
T(n) = O(f(n)) if eventually for all sufficiently large n, T(n) is bounded above by a constant multiple of f(n).
T(n) = f(n) iff there exist constants c>0, N>0, such that T(n)>=cf(n) for all n>=N
O(f(n)) indicates the upped bound of a function, which both statements regarding the bubble sort are correct: T(n) = O(n*n) and T(n) = O(n*n*n)
What most algorithms designers usually interested in is θ(n).
Similarly to O(n), θ(n) is an asymptotic function. T(n)=θ(n) iff there exist constants c1>0, c2>0 and N>0, such that c1*f(n) <= T(n) <= c2*F(n)

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Matrix Factorization: initial values

The initial distribution of feature values affects the results of matrix factorization (SVD) algorithm (this implementation). In this post, let's have a look at performance of SVD algorithm with different distributions of initial values. To conduct experiments, I used Lenskit framework and MovieLens100K dataset. The experiments includes three distributions:

1. Fixed values (0.1) (Fixed)
2. Random values (Random)
3. Popularity distribution for item features and random for user features (POP)

The difference between Venn Diagram and Euler Diagram

Both diagrams are based on the set theory. The main difference between Venn and Euler diagrams is that a Venn diagram shows all possible logical relationships between sets, while an Euler diagram only shows existing relationships. In other words, in a Venn diagram you have to depict each intersection between each set, even if the intersection is empty, while in an Euler diagram you only depict intersections that are not empty.
Suppose we have three sets:

Lenskit: Precision, Recall and NDCG

This post is dedicated to accuracy metrics in Lenskit framework.