# How to contribute?

Here you will have the possibility to discuss the solutions of exercises in Lecture 9.

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## Problem 4

Dear Isem Team,

I think there is a typo in Problem 4: It should state that SAS − 1A is a sectorial operator (which is true), not STS − 1T.

Nevertheless, I was wondering if you meant SAS − 1 is a sectorial operator. Thanks!

OrifIbrogimov 17:46, 13 December 2011 (CET)

Dear Orif, thanks! We meant of course "SAS − 1 is a sectorial operator". IsemTeam 17:43, 14 December 2011 (CET)

## L'viv Team

Dear L'viv Team,

your `solution' of Problem 6 works only if the semigroups commute. This is not assumed in the problem, as it is posed!

JurgenVoigt 22:08, 10 January 2012 (CET)