OCP

In other words, the OCP says that you can always add new code to an object, but should never change the design of old code.

https://medium.com/@severinperez/maintainable-code-and-the-open-closed-principle-b088c737262

A Rule of Thumb for Cohesion

from http://code.tutsplus.com/tutorials/how-to-write-code-that-embraces-change--net-29716

You can think of ISP as a higher-level cohesion principle.
When both UI classes depended on the Broker interface, they were similar to two classes, each having four fields, of which two were used in a method and the other two in another method. The class would have not been very cohesive.