How long is an opening?

@A14747AT said in #20:
> Um... how long did it take you to write this???

no clue. lost and lots of editing. i write till i drop or find my initial though again. which might take few convolutions. I hope i did not break any rendering device.

Hi. I enjoyed your analysis and presentation of the data. I do wonder whether you have addressed certain possibilities.

-I assume that because of matchmaking parameters the games are usually between similar ELO players?
-Does it make sense to use 5 seconds for all ELO quintiles? In other words, if you're using "bottom quartile for time use" to determine where the game breaks from "opening preparation" to mid-game, does each quintile for ELO break along a similar enough bottom quartile for time use?
-When you say "opening preparation," I assume you mean that players are making moves based on their knowledge of openings, either from study or prior games. It might help to explain your definition.
-In explaining "opening preparation," you could also address the possibility that play in an opening progresses from memorized/completely familiar moves to moves that feel intuitive but are not genuinely "prepared," and eventually into moves that take longer based on the complexity of the position and the skills and qualities of the player. I think that's especially true in fairly fast games, as opposed to longer time controls where a player might pause for full analysis as soon as a position becomes familiar or complex. I wonder whether there is some ambiguity there that you should resolve before you can use the data to draw conclusions about where opening preparation ends.
-I play a lot of fast games, and I can assure you that in my own playing what's happening can be better explained as purely intuitive moves punctuated by analysis to understand complex or diverging possibilities. Even with analysis, it's more intuition based than it would be in a longer time control game, because of the time constraint. I don't know what's true for others. In a very loose sense, the intuitive moves at the beginning are "prepared" because I have seen the patterns many times. The intuitive moves at the end are similarly "prepared" because those patterns repeat a lot.

ELO. Did you compute ELOs from the games, or is ELO standing for Glicko?.. The kind of things that are behind the figures, good to know.

How utterly boring

Lichess doesn't use elo.

An opening can last as long as a game is permitted to last. Rock your horsey back and forth without repeating the same position more than 3 times.

@Proleet said in #13:
> I was always taught that the opening ends when the rooks are connected.

This was just what I was looking for - an answer I could make sense of and then ponder how it works for me.

So, let's work from an example rather than using the data used to show the time it takes to make a move. (I'm not sure what is being shown by these graphs.) Lets use the Kings Gambit in Modern Chess Openings by Nick de Firman. Firman's analysis opens with (1) e4 e5 (2) f4 exf4 (3) Nf3 g5. (This is the traditional King's gambit opening, right?) Then Firman goes into his famous (infamous?) table structure, with the Column 1 being credited to Lionel Kieseritzky. (I have no idea where the moves in the unbranched column came from. They are not those played in The Immortal Game.) Kieseritzky's approach is described in 13 1/2 moves: (4) h4 g4 (5) Ne5 Nf6 (6) d4 d6 (7) Nd3 Nxe4 (8) Bxf4 Qe7 (9) Be2 Nc6 (10) c3 Bf5 (11) d5 Nb8 (12) Na3 Nd7 (13) Nb5 .... (It's great fun to set up the board after these moves and go after the chess engine!) Notice neither side has castled to this point. The rooks haven't been connected. (Nod to @Proleet) We have no idea how long it took Kieseritzky or his opponent to make these moves. (For all I know, Kieseritzky was playing his opponent by letter.) I'm a player who's rated at ~1300, mostly because I'm a good tactician rather than a solid planner. I find this sequence fascinating and have had great fun screwing around with it. Still, I have no idea where Kieseritzky's line transitions to a middle game, or if it's all part of the opening, or if undocumented moves exist before this line transitions to the middle game. (Firman notes that at move (13 1/2), white and black's chances are about equal. Does the middle game begin when one side's chances are better than the other's?) Some generalization for the transition between parts of the game must exist, but I'll be darned if I can find it. I'm looking for some insights on this. (It took about 30 minutes to write this, @dboing. If a good answer comes back, it's been worth every second.)

@cscottrun4it Youre comment kept me up late at night, so I had some quality time to think about it. I think in order to find a definitive answer to this question we must first ask ourselves: What is an opening? For me the meaning of the opening is the phase in the game where you develop your pieces. The moment you have developed all your pieces and castled your king is normally the moment you connect your rooks but obviously this is not a definitive answer. For example 2 amateur players might open their game like this 1.a4-a5 2.h4-h5 3.Ra3-Ra6 4.Rh3-Rh6. Now, both players have connected their rooks, be it on the 3rd and 6th ranks but still they are truly connected... Obviously no one in their right mind would consider the opening stage to be over at this point.

Sometimes when I play a studend I move my knights back and forth to give them time to develop some or sometimes all of their pieces to show them the strenght of a fully developed position. In that case I would consider 1 player to have reached the opening phase but the other (me who has the exact same position on move 10 as on move 1) to never have reached the opening phase. Still I would consider it the opening phase as long as atleast 1 of the 2 players is developing his pieces.

Having said that, what about a game where both players just start moving their knights back and forth, or maybe just dance around the board for 20 moves only to find themselves back at their starting squares a move later and agree to a draw on the next move?! I would say that eventhough a game like this would have 20 or more moves it never even reached the opening stage. Another fun idea would be that in the earlier mentioned game, the players didnt agree on a draw on move 20 but started playing an actual good game from that move. Then I think one can safely say that the opening of that game didnt start on move 1 but on move 20.

Joking aside, I think there is another way of determinating when an opening is actually over. And to get there I think we should change the question from where does an opening end to where does the middlegame begin? Having thought long about this question too I think my answer would be, that that is the moment where 1 side switches from the idea of developing to attacking! A good amount of games are played where one side starts attacking without having developed some (or sometimes almost all) pieces. For example in the French Winawer variant where white doenst move the bishop on c1 and the rook on a1 at all, the same goes for many other opening variants where the pieces are best developed on their starting squares. Ofcourse these games still have opening, middle and-endgames.

I think there are other ways to determine where the opening ends and where the middlegame begins. And although this could be a single point in time one could also think of it in this way; opening phase -> transition phase -> middlegame. I think that this is a very important idea of looking at the problem. For example if we translate the problem we have here to for example evolution, one might ask the question; where did homo erectus end and homo sapiens begin? The answer to this question is that there wasnt just 1 moment in time where this happened. There wasnt 1 homo erectus that had a homo sapien baby but it was more of a slow gradual process that transformed our species from opening to middlegame.

PS: Altought the transition from opening to middlegame can be marked as a point in time, i do not think that the time spend by the players is relevant to this question. The moment in time is linked to the position the players reach at that period in time and the position is the thing that should determine where the players are in the game.