응용수학 세미나
연사 : 이정엽박사 (한국고등과학원KIAS)
제목 : Pure point diffraction on substitution point sets
일시 : 2008.7.30 (수) 오후 2:00
장소 : 산업경영학동 3층 세미나실 3321호
초록: It has been known that periodic patterns in the plane or in three-dimensional space cannot have rotational symmetries of order greater than six and five-fold rotational symmetry. However this characterization is no longer true in diffraction point of view. In fact, one can observe that quasicrystals and Penrose tilings are not periodic, but show the diffraction images which consist purely of bright peaks (typical feature of periodic patterns) and have the forbidden (order greater than six or 5-fold) symmetries.
We look at "order" from the point of view of diffraction and understand the geometric structures which have long-range aperiodic order. When the diffraction image consists purely of bright peaks, we call the diffraction pure point diffraction. In this talk, we will mainly consider substitution point sets and determine the equivalent properties for the pure point diffraction.