v3 already lets you drill by theme. You have to do it unrated though.
The Play vs Computer has the option for some endgame drills. Don't know if your suggested material combinations are there. There is also a separate Drills section for practice.
Content of My Suggestion Ticket
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Hello Chess.com Members,
I just submitted a suggestion ticket regarding Tactics Trainer, the contents of which I'd like to share with you.
Hello Chess.com Caretakers,
I have spent 75+ hours on chess.com tactics trainer (TT), counting my past accounts. I feel strongly that following additional features to TT will make it a lot more useful and attractive to its users.
1. To the existing list of available tags which I found here, www.chess.com/article/view/chess-tactics--definitions-and-examples, following tags can be added :
color complex : many tactics and combinations are carried out on a single color complex
dark-squared color complex, light-square color complex : these two will add more detail
key square(s) : in endgame tactics like king pawn endgames, and the ones where you have to check/maneuver continuously to reach a key square, this tag would be applicable
The TT staff as well as zealous premium members will be able to add these new tags to the TT problems individually.
2. Theme Filter : A theme is learnt well and quicker if many problems are done on that theme at one time. eg, a beginner will be able to grasp the concept of 'interference' easily if he/she solves scores of problems on 'interference' in one session. Since currently TT gives shuffled problems from different themes, it's not easy for users to concentrate and learn a single theme they want to learn.
So if a filter option is available, based on the available tag list only, members will be able to solve problems themewise eg., one could choose 'mating net' option in filter column and practice them in one session today and 'pawn promotion' tactics in another session, the next day.
Even coaches who have to teach a particular theme to their students will find this useful. Say, one has to teach 'back rank' tactics on chesskid.com, they can set a particular rating range if required, in addition to this new theme filter, and demonstrate the back rank theme to their students.
3. Material Filter : Generally positions/problems having similar material in a particular stage such as endgame or middlegame, tend to have same fundamental nature and require similar or related approach for the solution. By similar material, I mean eg, two problems both featuring rook, knight, king for both Black and White, but say different number of pawns.
Even when these problems don't show obvious similarities, when a member selects to solve say, queen + two rooks problems, he learns a lot about how to look for approaching the heavy pieces endgames in any given situation/position.
Thus a 'Material Filter' can be created separate from 'Theme Filter' with its own tags as following :
QRB : queen, 1 rook and 1 bishop + same or different no of pawns for both sides
QRRB : queen, 2 rooks, 1 bishop for both sides
RM : 1 rook and 1 minor piece for each side
E : exchange
Ofcourse many such combinations of material would be possible, but maybe only the important or frequent dozen categories can be kept. Or another way, if the code is fixed, say only letters possible are Q,R,N,B or you can also add M and E for minor piece and exchange respectively, then the users will themselves be able to create these 'material tags' and filter the problems according to these.
I have given thought and come up with the above, but maybe your competent coders can find a smarter and simpler way to implement these features. Looking forward to your reply.
Thanks,
e4exclusive