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题目： The second obstruction and descent

报告人：吕昌 研究员（中科院信工所）

时间：2021年12月24日（周五） 上午9：00-11：00

地点：教二楼827

摘要：I shall start from several classical cohomological obstructions to local-principle. Then in a categrical fashion, I introduce my concept of ``descent by gerbes", which is an analog in the second cohomology level to the classical method of descent by torsors. This leads to some composite obstructions not larger than all known existing ones. Time permitting, I also mention the so-called derived obstruction.

简介：Chang Lv received his BS degree from Nankai University in 2010 and PhD from AMSS, CAS in 2015. Since then, he is a faculty member in IIE, CAS. His research mainly involves number theory, arithmetic algebraic geometry and cryptography. The results were published in Bull. Lond. Math. Soc., Acta. Arith., Sci. China Math., IEEE T. Inform. Theory, etc.

联系人： 方江学、张俊

主办单位：首都师范大学77779193永利官网、首都师范大学交叉科学研究院