The van Lamoen circle is named after the mathematician Floor van Lamoen [nl] who posed it as a problem in 2000.^[3][4] A proof was provided by Kin Y. Li in 2001,^[4] and the editors of the Amer. Math. Monthly in 2002.^[1][5]

The center of the van Lamoen circle is point ${\displaystyle X(1153)}$  in Clark Kimberling's comprehensive list of triangle centers.^[1]

In 2003, Alexey Myakishev and Peter Y. Woo proved that the converse of the theorem is nearly true, in the following sense: let ${\displaystyle P}$  be any point in the triangle's interior, and ${\displaystyle AA'}$ , ${\displaystyle BB'}$ , and ${\displaystyle CC'}$  be its cevians, that is, the line segments that connect each vertex to ${\displaystyle P}$  and are extended until each meets the opposite side. Then the circumcenters of the six triangles ${\displaystyle APB'}$ , ${\displaystyle APC'}$ , ${\displaystyle BPC'}$ , ${\displaystyle BPA'}$ , ${\displaystyle CPA'}$ , and ${\displaystyle CPB'}$  lie on the same circle if and only if ${\displaystyle P}$  is the centroid of ${\displaystyle T}$  or its orthocenter (the intersection of its three altitudes).^[6] A simpler proof of this result was given by Nguyen Minh Ha in 2005.^[7]

• Parry circle
• Lester circle