| Classes of Spatiotemporal Objects and Their Closure Properties Recent countries visiting this post |  |
 | 5 | United States |
 | 1 | Russian Federation |
 | 1 | Japan |
| Classes of Spatiotemporal Objects and Their Closure Properties Recent countries visiting this post | |
| 5 | United States |
| 1 | Russian Federation |
| 1 | Japan |