Hypocycloid prove that an epicycloid with "k" cusps moves snugly inside one with "k"+1 cusps. The evolute of a hypocycloid is an enlarged version of the hypocycloid itself, while the involute of a hypocycloid is a reduced copy of itself. The pedal of a hypocycloid with pole at the center of the hypocycloid is a rose curve. The isoptic of a hypocycloid is a hypocycloid. Curves similar to hypocyloids can be drawn with the Spirograph toy. Specifically, the Spirograph can draw hypotrochoids and epitrochoids. The Pittsburgh Steelers' logo, which is based on the Steelmark, includes three astroids (hypocycloids of four cusps).
Geometric and Functional Analysis "Geometric Aspects of Functional Analysis" of which Vitali Milman had been one of the main organizers in the previous years. The journal retained the same acronym as the series to stress the connection between the two. The journal is reviewed cover-to-cover in Mathematical Reviews and Zentralblatt MATH and is indexed cover-to-cover in the Web of Science. According to the "Journal Citation Reports", the journal has a 2015 impact factor of 1.476. The journal has four editors: Vitali Milman (editor-in-chief), Mikhail Gromov, Simon Donaldson and Peter Sarnak. Geometric and Functional Analysis "Geometric and Functional Analysis" ("GAFA") is a mathematical journal published