Kemeny-Young Optimal Rank Aggregation in Python

Category: python
#python #rank aggregation #kendall #tau #kemeny #kemeny-young #voting theory

Rank aggregation is a problem with many important applications and naive approaches to it go wrong in subtle ways. Let’s say that your national Quidditch league is dominated by five major wizard sports newspapers. Yes, the ones with moving images and everything. Every week after the games, each of them publishes a ranking of the star players. For now, let’s suppose that the set of players under investigation is always the same, as the problem becomes a bit more complicated otherwise. …

Inverses and pseudoinverses. Numerical issues, speed, symmetry.

Category: benchmarking
#inv #matrix inverse #numerical analysis #numerical methods #pinv #pinvh #positive semidefinite #pseudoinverse #symmetric #benchmarking #python

The matrix inverse is a cornerstone of linear algebra, taught, along with its applications, since high school. The inverse of a matrix \$latex A\$, if it exists, is the matrix \$latex A\^{-1}\$ such that \$latex AA\^{-1} = A\^{-1}A = I_n\$. Based on the requirement that the left and …