J. Posthumus
Last tournaments played
| Tournament | Date | Elo Avg. | Country |
| Grand Rapids-ch MI amateur | ??/??/1994 | 80 | United States |
| East Lansing ch-MI op | ??/??/1982 | 0 | United States |
Most Played Openings as White
| ECO | Opening | Games |
| E72 | King's Indian with e4 & g3 | 1 games |
| A40 | Queen's pawn | 1 games |
| E64 | King's Indian, fianchetto, Yugoslav system | 1 games |
| E21 | Nimzo-Indian, three knights variation | 1 games |
Most Played Openings as Black
| ECO | Opening | Games |
| A45 | Queen's pawn game | 1 games |
| E90 | King's Indian, 5.Nf3 | 1 games |
| B09 | Pirc, Austrian attack | 1 games |
| E76 | King's Indian, Four pawns attack | 1 games |


United States