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Some contributions to Crouzeix conjecture

• Date July 18, 2018
• Hour 12 am
• Room GSSI Main Lecture Hall
Essentially, the talk is devoted to the issue of bounding the operator norm $\| f(A) \|$ of a linear operator $A$ on a Hilbert space. After reviewing the notion of numerical range and the results for the disk, the conjecture of Crouzeix is presented and the interest of the topic in several relevant applications is commented. Finally, the recent proof that the numercal range is a $(1+\sqrt{2})$-spectral set is presented.