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DTSTART:20181028T020000
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UID:calendar.63634.field_date.0@mathematics.huji.ac.il
DTSTAMP:20210309T042928Z
CREATED:20180822T100021Z
DESCRIPTION:Date: \n\n2:30pm to 3:30pm\n\n\nSee also: Colloquium\, Events
& SeminarsLocation: \n\nManchester Building (Hall 2)\, Hebrew University
Jerusalem\n\n\nIn 1925\, Tarski asked whether a disk in R^2 can be partiti
oned into finitely many pieces which can be rearranged by isometries to fo
rm a square of the same area. The restriction of having a disk and a squa
re with the same area is necessary. In 1990\, Laczkovich gave a positive
answer to the problem using the axiom of choice. We give a completely exp
licit (Borel) way to break the circle and the square into congruent pieces
. This answers a question of Wagon. Our proof has three main components.
The first is work of Laczkovich in Diophantine approximation. The secon
d is recent progress in a program of descriptive set theory to understand
the complexity of actions of amenable groups. The third is the study of f
lows in networks. This is joint work with Andrew Marks.
DTSTART;TZID=Asia/Jerusalem:20181122T143000
DTEND;TZID=Asia/Jerusalem:20181122T153000
LAST-MODIFIED:20181116T060014Z
SUMMARY:Colloquium: Spencer Unger (HUJI) - A constructive solution to Tarsk
i's circle squaring problem
URL;TYPE=URI:https://mathematics.huji.ac.il/event/colloquium-5
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