Author: Komputer Korner
Date: 19:22:50 05/18/05
I have made my point but so few people seem to get it. People are confusing minimaxing and backsolving. Minimaxing simply lets one decide what path to follow. However backsolving would be very useful if you had the whole tree evaluated(that is every node). Then you could press a button and voila the whole tree would have annotations against every node and the winnng or drawing path would become clear. However we will never obtain this position, so why be concerned with having evaluations attached to only part of your ultimate opening repertoire? Having an opening repertoire involves a constant process of fixing holes and experimenting with new lines. It shouldn't be a process of evaluating endgame positions and proprogating the result back down the tree. If you are doing that then you are not using backsolving correctly. The study of openings is not the study of endgame positions. Who cares if a 40 move line has evaluations at every node if 99.9999% of the time, you will never meet that line in your play. The opponent will have veered off far sooner. So what has backsolving actually done for you? It simply has minimaxed it's way to attach evaluations to nodes in your opening repertoire. Backsolvers like to be content with the knowledge that the computer is helping them attach openining evaluations to all the nodes in their opening tree. They think the computer is doing useful work for them. However if they don't spend time analyzing the moves at the start of a game all they will have is a tree that has a precious few refuted lines that they should never play for one side and always play if allowed for the other side. Meanwhile non backsolvers do not care about the results of games. They care about the analysis of opening positions. They put the engines to work on opening problems and opening strategies. A number of posters who back backsolving think that I am against Bookup. I think Bookup is a great program. I simply claim that backsolving is an overhyped feature in the program. A number of posters have claimed that backsolving helps them with transpositions. Backsolving has nothing to do with transpositions. Let us take an example. Let us say that you have the moves 1.d4d5 2.c4c6 3.Nf3Nf6 4.Nc3 in your opening repertoire tree. Let us say that at the final position you have it analyzed as + .16 pawns for white. You backsolve it and then every node gets a +.16 evaluation attached to it. You then play a game as black against someone who opens up 1.d3. you probably should play 1...d5 or 1...e5 or 1...c5 but you reason 1...d6 is an acceptable move against most white openings therefore why not play it against 1.d3 Maybe your opponent will play 2.d4 so you play 1...d6. Now your opponent does indeed play 2.d4 in effect wasting the white half move opening advantage. However since you don't have these moves in your opening repertoire, if you play anything but 2..d5 you are on your own. So being a committed backsolver that you are, you play 2...d5 because now your opponent and you will be back in your bullet proof opening repertoire that you have built up by backsolving results of games. Since you have previously backsolved this position, indeed because of bookup's position based format, the transposition immediately brings you to the same node position as after 1.d4d5. So you are happy now, because from here on until the opponent veers out of your book, you will have an evaluation against any position you and your opponent reach. however if you had manually put the +.16 result of 1.d4d5 against 2.c4 yourself you wouldn't need to have backsolving do it. The point is that even in this simple example of backsolving, backsolving didn't help you discover the transposition. The transposition was already there just waiting to be played and waiting for Bookup to discover it. Automatic transposition paths in Bookup are a wonderful thing but backsolving doesn't discover the transpositions for you. Transpositions are only useful by going forwards not backwards. You don't play chess backwards. You play chess forward one move at a time. Of course you need an evaluation wherever you have a move choice. However the moves have to be already in the opening tree for backsolving to attach evaluations to them. Because the moves 1.d3d6 were not in your opening tree, backsolving couldn't attach an evaluation against these moves. It had only the position after the starting moves 1.d4d5 to attach moves to , not the 1.d3d6 position. of course, after 2.d4d5 Bookup automatically brings you to the node transpostion , but backsolving is not at work here. only after you put the moves 1.d3d6 2.d4d5 and then backsolve again will you have evaluations against those 1.d3 and 1.d3d6 nodes. Of course the .16 pawns evaluation automatically gets added to each node but that is not because of the magic of transpositions. Backsolving did that. . It backed up the .16 pawns right back to the begining of the game. however if you analyze the position with an engine at 2.c4 and the engine comes up with .16 pawns you can put the .16 pawns in yourself at that position. You don't need the .16 pawns evaluation at 3.NF3 or 4.Nc3 unless there are move choices at those position. if there are move choices you must have added them yourself. Either the evaluations at the other move choices were put in by backsolving or you manually added them. Either way they have to get there. in order for you to know which path to take. If the evaluations were put there by backsolving, what end position is it depending on? the 10th move, 20th, 30th 40th? The farther out you go the more worthless the evaluation. So even if you never backsolve any farther than the 10th move out, you still have to analyze any node where there is a move choice. The backsolvers will argue that with backsolving you already have an evaluation at every node and thus when you add a new move choice at a particular node, then you have saved the work of manually adding that evaluation to the 1st move choice that was at the node that you are adding a new move to. So this then is the ONLY ADVANTAGE OF BACKSOLVING. It will save you the work of adding the evaluation to a node that in the future will have another move alternative added to that position. THEREFORE I APOLOGIZE. Backsolving does have 1 advantage. It is interesting that no proponent of backsolving has pointed this out. However backsolving has a dangerous side to it that I have pointed out. This dangerous side is the fact that backsolvers will base their repertoire paths based on backed up evaluations that were made near the end of the game. These evaluations are very dubious. You should restrict your backsolving to no later than the 20th move in most lines (some book lines go out as far as 30 moves or later , so an exception can be made for those). Then you can backsolve in confidence knowing that you will save time in the long run by not needing to manually add those annotations. The important thing to remember is to only backsolve while you are in the opening . NO LATER. SO I REPEAT AGAIN, I APOLOGIZE.
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