| On the maximum number of edges in topological graphs with no four pairwise crossing edges Recent countries visiting this post |  |
 | 6 | United States |
 | 2 | |
 | 1 | Russian Federation |
| On the maximum number of edges in topological graphs with no four pairwise crossing edges Recent countries visiting this post | |
| 6 | United States |
| 2 | |
| 1 | Russian Federation |