An arrangement of pseudolines is a family of pseudolines with the property that each pair of pseudolines has a unique point of intersection where two pseudolines cross. An arrangement is simple if no 3 pseudolines have a common point of intersection.
S.Felsner in his paper "On the number of arrangements of pseudolines" presented an enumeration of simple arrangements of 10 pseudolines. This enumeration became an addition to the previous enumerations of simple arrangements on up to 9 pseudolines (due to Knuth).
I will also briefly talk about my work on enumeration of arrangements of up to 12 pseudolines.