**
Burr Tools
**
Many puzzle solving programs have seen the light of day.
Most of these specializing in one or two puzzles.
**Burr Tools** is a completely different type of program.

Produced by Andreas Röver this program
can be found on the homepage:

http://burrtools.sourceforge.net/

The current version is **Version 0.1.9**

**Burr Tools** capability is very different from most solvers,
because it allow all kinds of pieces and movement constraints.

There is also a 60 page long documentation that explains all of the
program you need to know to use it and also a bit of the internals.

BurrTools is not only capable of solving SOMA puzzles. It can
currently solve everything made out of cube units and that is
assembled in a cube grid.

Besides finding the possible ways to align the pieces to make the requested
target shape the program can also analyze how the pieces can get into this
position. That is even possible for puzzles where you need to shift the
pieces around before it falls apart. You get nice animations to show you how
to assemble the puzzle.

There is one assembly algorithm that does the search for assemblies. The
algorithm is based on Donald E. Knuths "Dancing Link" Algorithm. There is a
link for it on the webpage. The basic idea of this algorithm is as follows:

First transform the problem into a table. In this able each row corresponds to
one possible placement of one piece inside the result shape that you want to
assemble. And there are n+m columns. n for the number of pieces and m for the
number of cubes that the result containt.

So let's see what is might look like for the "Soma Cube". Here the table has
7+27 = 34 columns. 7 for the pieces and 27 for the 27 unit cubes of the final
cube assembly. Now each piece gets some rows. The 3 unit piece has 144
possible ways to put it into the cube (12 rotations times 12 places for each
rotation). The T shaped piece has 72 rows (12 rotations times 6 places for
each piece) and so on.

In each row of the table you have either a 0 or a 1. You have a one in the
column of the piece and you have a 1 in the columns that stand of the cubes
that are occupied by the piece in the placement that the row stands for.

Now all that needs to be done is find a set of lines from this table so that
there is exactly one 1 in each of the columns of the selected set of lines.

The SOMA cube with solutions *for Burr Tools* is found here
N060602SomaCube.xmpuzzle.

Lets look at this impressive feature list:

**:)** Will help you solve a certain kind of puzzle. Namely puzzles that are made out of square or dice shaped units and whose solution also contains only rectangular aligned pieces.

**:)** Does nearly all that PuzzleSolver 3D which is

**:)** You can enter all puzzles that are assembled out of dice shaped units

**:)** Find assemblies for you puzzle

**:)** Disassemble the found assemblies

**:)** Show everything in a 3 dimensional image

**:)** Animate how the puzzle has to be assembled

**:)** Toggle the visibility of pieces in the solution to have a look at the inner workings of a puzzle. This is especially helpful for box packing puzzles

**:)** Runs on Windows, Linux and OSX and probably other Unix variants as well.

**:)** You can specify which cubes to fill and which can be empty or full. PuzzleSolver 3D has only 2 modes. Either all cubes may be left empty in the solution, or the cubes that have an empty neighbor must be filled. BurrTools are more flexible here.

**:)** More than one problem in one file (e.g. have several Soma Cube problems in the same file)

**:)** Constraints to piece placements (like checkerboard)

**:)** Group pieces together to tell the disassembler that they don't need to be taken apart. This is necessary for puzzles like "Cube In Cage" where the cage can not be taken apart but has 3 movable pieces

**:)** No limits (or at least very high limits) to sizes and number of shapes. As long as your computer has the memory and you the patience the program will do it for you, even if it takes eons.

**:)** Create images that contain the pieces, or an instruction how to assemble the puzzle

**:)** Free as in beer. It doesn't cost you anything

**:)** Free as in speech. The source is available, so you can do your own programming or help me writing this software or even continue improving the program in case I have to stop working on it.

**:)** Save puzzles with solutions in compressed XML-files. This allows you to create puzzles with other means (like your own burrgrower, ...)

**:)** A library is provided that helps you to write your own software for puzzle design and analysis

*Submitted (2.june.2006) by Andreas Röver <roever@users.sf.net>*

*Edited by Thorleif Bundgaard <thorleif@fam-bundgaard.dk>*

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