I am still learning chess (been playing ~6 months steadily now and am at ~1300) and have recently been enjoying correspondence chess with a 3 day time control. I find it gives me time to really analyze each move without the pressure of time that I get with blitz games.

I have been trying to learn new openings in detail, mostly using opening explorer in lichess or chess.com. As most of you probably know, it breaks down the most popular moves in the opening from games played and gives the % outcome of white wins/black wins/draw for each move. This is an amazing resource for someone like myself who doesn't have lines memorized yet, but is it unethical to refer to these resources during a daily game?

I would never refer to an engine for a current game and the opening explorer is only showing the data for games that have been played, not evaluating positions, but I still wonder if it would be wrong to use.

What is the general consensus of the online chess community on this?

  • 1
    Agree Rewan. I only mentioned computers in my answer to take it one step further. Commented Jan 21, 2020 at 17:17
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    Opening explorers are game databases. It's a good question, but indeed a duplicate -- the missing link is to realise the opening explorers == databases of games of that site.
    – Remellion
    Commented Jan 21, 2020 at 17:43
  • Oh I didn't realize they were equivalent, sorry. Nothing came up when I searched before posting.
    – lukehod
    Commented Jan 21, 2020 at 17:51
  • I think using a opening book is better than using an opening database, but at least the book can explain the ideas. Also, I believe using too much reference for the opening can become a bad habit. I think one must either learn a few openings or think about the position alone.
    – Marcelo
    Commented Feb 16, 2020 at 19:59

2 Answers 2



ICCF: Says nothing about it, or assistance of any kind, and you can even use computers legally. Here are their rules.

USCF: "3. You may consult chess books and periodicals but not other players." Here are their rules.

With regards to the ICCF rules, my guess is that they just decided it was too hard to police computer used, so they just allow it. Books have always been permitted.

  • Rules change all the time. When I played ICCF specifically allowed reference materials. Commented Jan 21, 2020 at 17:31
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    Of course, rules change all the time. My guess is that computer use led to this "subtraction". If you cannot police computers, why would you even attempt to police book use, therefore, they removed it. Commented Jan 21, 2020 at 17:33
  • They never policed book use. Strange they just didnt add computers etal later. Commented Jan 22, 2020 at 3:50
  • I never said that they did. I was just saying, they removed any reference to it being allowed since it is a moot point considering they removed any reference to computers even. Commented Jan 22, 2020 at 11:05
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    Again, please provide a link. Commented Feb 26, 2020 at 3:37


All correspondence chess always allowed written materials.

Now they may also allow computers, and AFAIK also do so as it would be impossible to know if someone was using one or not.

Many people now complain that CC is just one computer versus another.

I always suspected that Hans Berliner had used a computer when he worked at FSD in Gaithersburg for IBM as he showed some computer chess programs at the DPD datacenter in DC.

You need to be careful with what looks like winning percentages in those databases. I have found you can pick the move that seems the best and then the next move by the opponent he has options that are better than what you thought you had picked.

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    There's a bias built into databases, especially concerning modern games. A line gets played, and a position is reached, say 1000 times, in which White has typically shown an advantage, so the stats tremendously favor White. Then an enterprising player discovers a hidden idea for Black, and refutes the line; it now favors Black. White stops entering that line; ergo, the stats for it still favor White, even though the position (and current play) does not.
    – Arlen
    Commented Jan 21, 2020 at 17:30
  • This is beyond bias. It is an artifact of the statistics. Or rather an artifact of misuse of statistics. You can pick the best moves for several in a row and then discover that the opponent has an overwhelmingly winning position statistically. Commented Jan 21, 2020 at 17:49

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