porism

n.

不定设题，系论；

porism
Porism
Poncelet porism in two circles.
Poncelet's porism in the finite real plane
Developments on the porism of the in-and-circumscribed polygon
LI. Developments on the porism of the in-and-circumscribed polygon
On Cayley’s explicit solution to Poncelet’s porism
On the rotation index of bar billiards and Poncelet’s porism
LXXI. On the porism of the in-and-circumscribed triangle, and on an irrational transformation of two ternary quadratic forms each in...
The Collected Mathematical Papers: On the porism of the in-and-circumscribed polygon, and the (2, 2) correspondence of points on a c...