All examples in this problem include three or fewer outlines of circles and (non-skinny) triangles.
M. M. Bongard, Pattern Recognition, Spartan Books, 1970, p. 220.
Adjacent-numbered pages: BP16 BP17 BP18 BP19 BP20  *  BP22 BP23 BP24 BP25 BP26
finished, traditional, bongard
circle_triangle_outlines [smaller | same | bigger]
Mikhail M. Bongard