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Rules to solve problems

1. Tactical problems are not only evaluated on material; a full assessment of the position is made also. It's my opinion that this makes the training more complete since you have to consider not only the tactical motif but the entire game.
2. In every tactics problem you need to gain a least 2 pawns equivalent score. Considering point 1 above; it is possible that the correct solution implies a material gain of only one pawn and the other one is achieved by positional elements.
3. If you make a move that is weaker than the best one, but its score is greater than the equivalent of 2 pawns value, the system tells you that is a good move but that there is a better one and lets you retry. If the move score is under 2 pawns your solution is considered wrong.
4. For the last required move; if its score is over 5 pawns the problem is considered correctly solved even if there is a better solution from the computers point of view.
5. The solution always shows the complete computer best line but only the moves in bold typeface are required to successfully resolve the problem.

I don't see the chessboard

Does Ideachess run on a Mac computer?

Usually yes, you need Java installed. I don't have a Mac so I don't know how to help you installing Java if it's not already on your computer.

Does Ideachess run on Linux?

Yes. All the development of Ideachess is done under Linux. If you have problem with the IcedTea Java plug-in remove it and install the Sun one.

How does the Ideachess tactics rating system work?

Ideachess implements the Glicko rating system.
The player and the problem are considered as opponents and both have their rating adjusted after each solution is attempted. If the player fails to solve the problem their Elo is lowered and the problem Elo is raised and vice versa. The amount the Elo changes depends on the Elo difference between the two and the RD parameter. RD stands for Rating Deviation and measures the accuracy of a player's rating; the lower the Rating Deviation the more accurate the rating. When a new player registers on Ideachess their rating is set to 1500 and their RD to 350. It's about the same when a new problem is added on the Ideachess database.

How is the best solution determined?

The best line is found using the open source chess engine Stockfish with 20 sec thinking time. The internal chess engine that evaluates alternative solutions is much weaker but it's optimized for tactical positions; it's Elo rating is over 2000.

How are the pieces valued on the applet embedded chess engine?

Queen = 10 points, Rook = 5 points, Bishop = 3 points and Knight = 3 points

Active players and tactics ranking

Only active players are shown in the tactics ranking.
A player is considered active if they have attempted at least 10 Elo tactics problems in the last 30 days. The active status is not updated in real time, because it is computational heavy, it is upgraded once every few days. I do it manually with a store procedure.

Problem's quality

It’s important that after attempting the puzzle you express your quality rating by assigning a vote from 1 to 5 stars:

1 star: the problem is bugged/very annoying.
2 stars: you don't like it.
3 stars: Ok
4 stars: is a nice problem.
5 stars: is a very nice problem.

The puzzles with very low votes will be removed after some time on a statistical basis, so the average quality of the problems will rise.
The "rating" measured by the stars is about the quality of the problem and NOT the difficulty of the problem!

The solution ... should be accepted

I can't force the chess engine to accept a specific solution, all is done automatically. Give the problem a low quality rating, 1 or 2 stars, and it will be removed as soon as it has a statistically significant number of votes.

Do the problems get harder as the player's rating gets higher?

Yes, problems are assigned to you according to your Elo. For tactical problems an Elo is choosen between your Elo and your Elo-400 points. For mates problems between your Elo and your Elo-600 points.
Remember that newly added problems have an inaccurate Elo rating. The problem RD value indicates how accurate it is. With more attempts by the players to solve the problem its RD will lower and the problem's Elo will become more accurate.

Tactics/Checkmate problems ratio

In the Elo rating tests are assigned with 60/40 % ratio

Does the time used to solve a problem affects the Elo variation?

No. The time is measured only for statistical purposes.

Where do the problems come from?

Almost all the problems come from real games. Every week I analize the Week In Chess PGN files to find interesting tactical positions from the major world wide chess tournaments.
For more than 2 years I have had at least one computer, and often more than one, running software written by me analizing games 24 hours a day for 7 days a week!

What are the ratings of those four silicon computers?

I don't know exactly, I think the strongest one, 38911, is around 2200 Elo.

38911 search deep limited to 6 half moves
Zeta search deep limited to 4 half moves
Vic search deep limited to 2 half moves
Valvolo search deep limited to 2 half moves and often choose its move randomly!

I cannot copy the FEN string. I mark the string and press CTRL + C in the box but it doesn't work.

With the latest Java releases (from Java 6 Update 24) Sun has changed the security policy about using the clipboard to copy text and this function doesn't work anymore.
To solve this issue I've put the FEN string under the chessboard so you can copy it directly without using the button on the applet.

I've lost xxx Elo points for a bug in a problem, can you give me the points back?

I'm sorry, no.

Is it possible not to be set the same puzzle more than once?

No, because it would require too much space in the database to store all puzzles attempted by all the users.

I don't get the deal with "Mate in X" problems that has a very easy solution in X+1 steps, and a hard one in X steps. Why should I bother?

Chess is an intellectual exercise. If your oppenent can find mates in X and you can only find them in X+1 the chances are you will lose!! (Datr)

Donations

If you like Ideachess and want to support its developement you can make a donation using the Paypal donate button on the right side of the main page of Ideachess for logged in users.
I remove advertiser's banners for the player's account that made a donation.

Acknowledgements

The used chess pieces are designed by Eric De Mund / CC BY-SA 3.0
Zuril

Posts: 187
Joined: Sun Jan 03, 2010 10:16 am
Location: Italy

Re: FAQ - Frequently Asked Questions

Improved text for FAQ.

The player and the problem are considered as opponents and both have their rating adjusted after each solution is attempted. If the player fails to solve the problem their ELO is lowered and the problem ELO is raised and vice versa. The amount the ELO changes depends on the ELO difference between the two and the RD parameter. RD stands for Rating Deviation and measures the accuracy of a player's rating; the lower the Rating Deviation the more accurate the rating. When a new player registers on ideachess their rating is set to 1500 and their RD to 350. It's about the same when a new problem is added on the ideachess database.
DATR

Posts: 27
Joined: Sun Oct 30, 2011 10:34 pm

Re: FAQ - Frequently Asked Questions

The best line is found using the open source chess engine Stockfish with 20 sec thinking time. The internal chess engine that evaluates alternative solutions is much weaker but it's optimized for tactical positions; it's ELO rating is over 2000.

Note!! evaluates
DATR

Posts: 27
Joined: Sun Oct 30, 2011 10:34 pm

Re: FAQ - Frequently Asked Questions

Only active players are shown in the tactics ranking.
A player is considered active if they have attempted at least 10 ELO tactics problems in the last 30 days. The active status is not updated in real time, because it is computational heavy, it is upgraded once every few days. I do it manually with a store procedure.
DATR

Posts: 27
Joined: Sun Oct 30, 2011 10:34 pm

Re: FAQ - Frequently Asked Questions

The puzzles with very low votes will be removed after some time on statistical basis, so the average quality of the problems will rise.
The "Average rating" of the stars is about the quality of the problem and NOT the difficulty of the problem!

Note
a statistical basis
DATR

Posts: 27
Joined: Sun Oct 30, 2011 10:34 pm

Re: FAQ - Frequently Asked Questions

I can't force the chess engine to accept a specific solution, all is done automatically. Give the problem a low quality rating, 1 or 2 stars, and it will be removed as soon as it has a statistically significant number of votes.
DATR

Posts: 27
Joined: Sun Oct 30, 2011 10:34 pm

Re: FAQ - Frequently Asked Questions

Do the problems get harder as the player's rating gets higher?

Yes, problems are assigned to you according to your ELO. For tactical problems an ELO is choosen between your ELO and your ELO-400 points.
Remember that newly added problems have an inaccurate ELO rating. The problem RD value indicate how accurate it is. With more attempts by the players to solve the problem its RD will lower and the problem's ELO will become more accurate.
DATR

Posts: 27
Joined: Sun Oct 30, 2011 10:34 pm

Re: FAQ - Frequently Asked Questions

Almost all the problems come from real games. Every week I analize the Week In Chess PGN files to find interesting tactical positions from the major world wide chess tournaments.
For more than 2 years I have had at least one computer, and often more than one, running software written by me analizing games 24 hours a day for 7 days a week!
DATR

Posts: 27
Joined: Sun Oct 30, 2011 10:34 pm

Re: FAQ - Frequently Asked Questions

Zuril

Posts: 187
Joined: Sun Jan 03, 2010 10:16 am
Location: Italy

Re: FAQ - Frequently Asked Questions

Is average-time calculated on the correct answers or all?

I'm trying to understand if I'm slow or many people attempt to answer in 30 seconds.

PS: I apologize about my eng
Nirvanus

Posts: 3
Joined: Tue Mar 17, 2015 4:41 pm

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