摘要：Higher Deligne--Lusztig theory uses l-adic cohomology to construct
smooth representations of reductive groups over complete discrete
valuation rings. In this talk, I will first take a glance at the Harish-Chandra
theory, and then give an introduction to Deligne--Lusztig theory, from
the classical finite field case to the local ring case. If time permits,
I will also report some recent works (joint with Stasinski) concerning
the associated representations.