Spirograph a hypocycloid. Spirograph Spirograph is a geometric drawing toy that produces mathematical roulette curves of the variety technically known as hypotrochoids and epitrochoids. It was developed by British engineer Denys Fisher and first sold in 1965. The name has been a registered trademark of Hasbro Inc. since 1998 following purchase of the company that had acquired the Denys Fisher company. The Spirograph brand was relaunched worldwide with original product configurations in 2013 by Kahootz Toys. In 1827 English architect and engineer Peter Hubert Desvignes developed his "Speiragraph", a machine to create elaborate spiral drawings, intended to prevent bank note forgeries.
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