2001/11/23 在 2001TMS 35屆數學年會首度發表 ( 2003/10/05補登 )。
2002/10/27 貼上這首頁的 GIF Animation 列表，有高達四個移動組件(up to 4 movable components)的家族譜，總共有多少成員呢？
方塊環玩法必須少一片，X型片在中央打轉甚是有趣！另外少 S 型片的解答在 Note 2.0 第 4號圖(第三頁右下)。
ref: Puzzle will be played... by ISHINO Keiichiro 石野 恵一郎，「18巧板」許多玩法的全解數請參考 18 ProTangram – Kao
ref: The Poly Pages by Andrew Clarke / Problems / Similar Hole Problems
Enlarge the Tetratans twice as the original ( as the black patterns shown on top ), put the black hole anywhere on the 6*6 fixed frame, and then fill in the other area with 18 ProTangrams.
It is much more difficult when the pattern left resembles the black hole.
Too bad there's no solution for the pattern H ?