Tesuji are skillful tactical plays in the game of Go, and the aim of many tesuji problems is to capture stones. MadLab is a program that solves such problems, even when the problems are open-space, not enclosed by outer walls (like semeai or life & death problems). MadLab analyzes a given problem (see examples below) until a solution is found, and the underlying algorithm guarantees that if a solution is found, it is 100% definitive. This makes the program well suited for learning purposes, and to get you started the program comes with 997 tesuji problems extracted from real high-level games for you to solve!

Another way to improve your tactical ability is to have your own games analyzed by MadLab. After you have played a game, MadLab can scan through it move by move and mark those stones that can be captured (an example of whole game analysis is given below).

December 2011: MadLab has been a commercial program. But as the author has his hands full with other software development at the moment, the full MadLab version is offered free of charge to the Go community.

Tesuji example 1: Black to capture the two white stones at 'a'

See the answer to the problem here. MadLab solves problems without relying upon patterns or other kinds of hand-crafted knowledge. So you may add or remove stones as you like, to see if and how this influences the solution. Three other examples are given below:

Tesuji example 2 (double-threat)
Tesuji example 3
Tesuji example 4

Whole game analysis

If you ask MadLab to analyze a game, the program will scan through the game move by move and mark those stones that can be captured (either as a normal or double-threat capture) or are dead. The marks look like this:

[The position is move #152 of this game (Yoda Norimoto (B) / Cho U (W))].

The three white stones marked with a black circle are proven dead (can be captured even if White moves first). The stones marked with "?" can be captured if the other color moves first. Finally, some stones are marked with "?2" and are connected with a yellow line. This indicates a double-threat tesuji. There are two such pairs of stones (one black pair at the bottom left and one white pair at the top left). For instance, regarding the black pair at the bottom left: the marks indicate that White can capture either the lonely black stone or the block of five black stones. You can see more details and examples regarding the analyze functionality here:

Another analyze example (more detailed)

The more time MadLab is given to analyze a game, the more tesuji's it may see. Note that this software does not play Go as such -- it solves Go problems and analyzes games (however, when solving a problem, you can have the computer play one of the sides).