Trees are easily one of the most important tools players have at their disposal. A tree is a way to organize every known position in an order that allows you to see immediately all the moves known from and to a position, the number of games containing that position, and the percentages showing the results of the games with the position. For opening preparation the advantages of this tool cannot be emphasized enough. For example, if a move you are considering is not in the tree, then you immediately know it is a theoretical novelty. In order for all this to be of practical use, the Chess Assistant team has worked hard over time to reduce the size of the tree itself (the space it occupies in your HD) and the time required to build it.
There are essentially three different trees for a base:
CA Tree this tree is both the smallest to build and the slowest to move through. Though moving from one move to another can be done in less than a second in average, jumping from one position to another several moves away can take a few seconds more. The biggest advantage is that it is so far the fastest one to build and the most compact one.
Direct Tree This tree is the fastest to navigate through and allows you to get the information instantly from any position. The Direct Tree can serve as an actual object and be removed from the base where it was built to be accessed anywhere (such as from a CD). There are many options to allow you to reduce the size of the tree (and the time to build it, of course), such as including only those positions that occurred at least twice, and then adding a game continuation as a note.
This allowed us to build a Direct Tree for the Hugebase (2.710 million games) that takes up only 480 Mb and that is included on the CD. (Chess Assistant 8.1 Mega Packet includes full CAP data (451 Mb)). In Chess Assistant 8.1 you can also build Direct Trees for a dataset, and enjoy other options such as choosing annotations to be included as positions in the tree or as pop-up commentary.
CA Professional Tree This is the big brother to the CA Tree above, and is the largest and fastest tree you can build for a base. It is a complete position-based tree like the Direct Tree, though inseparable from the base, and allows you to access instantly all the information from any position. Please note that the tree includes not only opening moves but also every position from every game with all the statistics. Although its true that it takes longer to build, and takes up considerably more space, it wont take your computer days to create, nor will it require a separate HD to store. For the Hugebase (2,710,000 games updated by October 1, 2004) this equated to 1.53 Gb (455 Mb for the base and 1.13 Gb for the tree). On an Athlon 1 Ghz with 256 Mb Ram, it took 52 minutes 48 seconds to build.
CAP is a special project created and run by Dann Corbit, with strong support of Convekta, and stands for Chess Analysis Project. It is a project designed to have a computer program analyze positions for several minutes and collect all the results into a single base. Vast majority of these positions are from openings, so when you see opening moves displayed in the tree with 0 games and an evaluation in the CAP column, these are the alternate suggestions made by programs, but that have yet to be tested in a game. Chess Assistant 8.1 comes with more than 10 million positions in the CAP tree of which more than 7.5 million are opening positions.
If you work directly with the tree window, then you can also directly edit the tree, include your own annotations (variations and commentary) and evaluations, not to mention running the engine, of course. It is here that you'll see an additional possibility of not only the known moves from the position but also the moves that lead to the position. You can call up a small window to see the different paths that lead up to it, so that you can not only see the last few moves that lead to the position but the entire line. If this is new for you, you'd better stock up on aspiring as you're getting ready to discover the world of transpositions as only Chess Assistant can show you.
For example, we are often told that a position such as below one, with the classic isolated d-pawn, can occur from many different move orders and it is often used as an example of the flexibility of openings.
With Chess Assistant you cannot only quantify exactly how many many is, but also see what every one of those other lines are in a small pop-up window. You can then click on the moves in it and see how those move orders ended up transposing to the position on the board. As you can see the screenshot below, according to the Hugebase (2,710,000 games) the position above has arisen from 63 different move orders, of which 25 were in 8 moves, and 38 were in 7 moves.
Since you can now build a quick direct tree for a set of games, you will also find a whole new world of opening preparation available as you watch not only the moves your opponent prefers in the tree made from his games, but also see the results/statistics from the other trees either by using the drop down menu at the top to flip from tree to tree, or by using the convenient shortcuts created to accelerate your work ([Shift] [F1]; [Shift] [F2]; [Shift] [F3]).
Long time users of CA know that there is an extremely powerful tree window that appears when stepping through the moves of a game. Now, the moves and variations from the current game are highlighted in yellow in the tree.