报告地点：行健楼学术活动室526
邀请人：黄益副教授
摘要：Grafakos systematically proved that A_\infty weights have different characterizations for cubes in Euclidean spaces in his classical textbook. Very recently, Duoandikoetxea, Mart\'{\i}n-Reyes, Ombrosi and Kosz discussed several characterizations of the A_{\infty} weights in the setting of general bases. By conditional expectations, we study A_\infty weights in martingale spaces. Because conditional expectations are Radon-Nikod\'{y}m derivatives with respect to sub-\sigma-fields which have no geometric structures, we need new ingredients. Under a regularity assumption on weights, we obtain equivalent characterizations of the A_{\infty} weights. Moreover, using weights modulo conditional expectations, we have one-way implications of different characterizations.
