On the nearly free simplicial line arrangements with up to 27 lines

In the present note we provide a complete classification of nearly free (and not free simultaneously) simplicial arrangements of d ⩽ 27 lines

The containment problem and a rational simplicial arrangement

Since Dumnicki, Szemberg and Tutaj-Gasi\'nska gave in 2013 in [9] the first example of a set of points in the complex projective plane such that for its homogeneous ideal I the containment of the third symbolic power in the second ordinary power fails, there has been considerable interest in searching for further examples with this property and investigating into the nature of such examples. Many examples, defined over various fields, have been found but so far there has been essentially just one example found of 19 points defined over the rationals, see [16, Theorem A, Problem 1]. In [12, Problem 5.1] the authors asked if there are other rational examples. This has motivated our research. The purpose of this note is to flag the existence of a new example of a set of 49 rational points with the same non-containment property for powers of its homogeneous ideal. Here we establish the existence and justify it computationally. A more conceptual proof, based on Seceleanu's criterion [20] will be published elsewhere [17]