Analysis of co-authorship in mathematical journals of Math-Net.Ru

Problems of co-authorship in mathematical articles were studied on the basis of journals data stored in the All-Russian mathematical portal Math-Net.Ru for the period from 2000 to 2020. The investigation shows that 191 the most articles (more than 59 are written by a group from 2 to 4 co-authors. 2 scientific groups consisting from 5 to 44 co-authors. Such a structure of coauthorship shows that the known tendency of deliberate growing co-authorship does not correspond to our object of investigation. We show that the main features of the co-authorship graph, such as a fraction of the vertices as a part of the maximal connected component, diameter and the average path length are stabilized once the number of co-authors reach 4. Unlike the recommendations to allocate articles written by more than 10 co-authors to a separate category, in our work we can allocate publications written by 5 co-authors to such a single category.