Questions about gershgorin-sets, gershgorin-disks, gershgorin circle theorem, brauer-cassini-ovals, brauer-sets, brualdi-sets, pupkov-solov-sets

Questions about Gershgorin sets, Gershgorin disks, Gershgorin circle theorem, Brauer-Cassini ovals, Brauer sets, Brualdi sets, Pupkov-Solov sets.