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Public Lecture: The hat, the turtle and the spectre

July 27, 2023 @ 8:00 pm - 9:30 pm

Come hear about the recent solution to a longstanding unsolved problem in geometry: it is possible for a single shape to tile the plane without any sort of repeating pattern? The “hat”, it turns out, solves this problem. It’s the first known aperiodic monotile, also known as an “Einstein”. In this public lecture, Craig Kaplan from the University of Waterloo (a member of the collaboration that discovered the “hat”), will talk about some background concepts from tiling theory and the history of the search for aperiodic shapes. The story of this discovery of the hat and the proof of its aperiodicity, as well as two other closely related shapes, the “turtle” and the “spectre”, will dazzle you with their application to derive more results about aperiodic tilings.

This talk will be in the Irving Oil Auditorium in the Richard Murray Design Building on Thursday, July 27 from 8:00 pm – 9:30 pm.

Read more about the recent discovery of the aperiodic monotile:


July 27, 2023
8:00 pm - 9:30 pm


Dalhousie University
Halifax, Nova Scotia Canada


Sanjeev Seahra