how are the problems on tactics trainer selected?



I'd like to ask how are the problems for the tactics trainer selected by the computer? Do they become more difficult as your rating gets higer? A staff member would be welcomed to answer :) 


Might I write my opinion ?

The problems on tactics trainer become more difficult when your tactic's trainer rating becomes higher. When you solve a problem, you can see somwhere your new rating and a + or - and a number, and the problem's rating and a - or +. So these ratings have not a really big difference. Eg, your rating is 1800 and you solve a problem with rating 1775, you are going to gain some points, and the problem is going to lose those points.

Hope I answered your question !