P. Petrov, G. Kostadinov, P. Zhivkov, V. Velichkova, T. Balabanov. Approximated Sequences Reconstruction with Genetic Algorithms

Кey Words: Reconstruction; sequencing; genetic algorithms.

Abstract.  Sequences reconstruction is a problem often met in many research areas. The core of this problem is how to recreate a full sequence of ordered information when only chunks of it are known.
Sequence reconstruction is applied in fields like genetics, cryptography and encoding. In this research, an approximate reconstruction of sequences is proposed, which is applied in the gambling industry for reverse engineering of slot machine virtual reels. The importance of this problem is related to the control of gambling games parameters by law regulators. The problem in this research has a combinatorial nature. The analyzed sequences are taken from commercial slot machine games. When the gambler spins the virtual reels he/she does not know how symbols are distributed on the reels. The gambler sees only small parts of the reels when they are stopped. By observing the game for a long enough time the gambler can record these small parts of the reels observer on the screen.
Collecting enough information the gambler can try to reconstruct all positions of the symbols on the virtual reels. Such reconstruction is not trivial, because there is too much unknown information. If there are absolutely identical repeating patterns on the virtual reels the gambler can not find this out by just observing small chunks.
Reverse engineering is commonly used during the analysis of slot machine gambling games. There are many approaches such reverse reconstruction to be done. In most cases, the goal of the engineers is to reconstruct the virtual reels completely. The reconstruction is similar to puzzle solving by attaching each observed piece with a proper corresponding one. Such reconstruction is not always possible because in some cases there is more than one way of connecting the observed pieces. The contribution of this study is related to the approximate reconstruction of the sequences. It does not give a direct solution to the reconstruction problem. Instead of this, it gives an approximate solution. The goal is a little bit changed from the exact reconstruction of the virtual reels to the construction of such reels which will give close behavior of the slot machine gambling game if they are loaded inside the machine instead of the original reels. The innovative approach is that the search for a sub-optimal solution is done in the space of the chunks instead of in the space of the sequences. The proposed approximate reconstruction is approved by experiments with real industrial data.