Introduction to the Chess Engine

Chess is mathematically unsolvable. But at the end of the day, the machine doesn't have to solve the game. The machine has to win the game. And to win the game, it just has to make fewer mistakes than humans...

— Garry Kasparov 

Chess is a complex games. There was a time when only man can play it, and nothing else. Today, chess computers play far more accurate then Man, and continues to improve at a fast rate, since Deep Blue beat Gary Kasparov in 1997, to now when Stockfish, the strongest chess engine, sits at a rating of 3800.

Why is engines important? Because we use them for many things, analyzing positions, holding champions between each other, farming content, playing against Mittens (scary) and so much more! 

We will be looking at how engines work, their history, and how they play. Enjoy!  

How It Works

Before the chess engine was developed, it had to go through a set of challenges before we get to where we are today. The engine works by forming a tree, which is a diagram of every possible move, what move the opponent can play, how the computer can move in that position, and so on. The engine analyze the position and makes the move into a number based on things like material, space, or king vulnerability. The higher the number, the better the move.

Because the engine can calculate so much, the engine has a fixed depth, which is a limit on how much it can calculate. It also runs through the Alpha Beta Pruning Algorism, which sort out unnecessary branches (Branches that start with a blunder or mistake) and look through the ones that start with the best moves. The engine also does a Quiescence search which extends beyond the depth to look at dangerous positions and to see possible solutions. 

These are the fundamentals on how an engine works.

History

In the past, Grandmasters came to our computer tournaments to laugh. Today they came to watch. Soon they will come to learn.

— Monty Newborn | 1977 

Over the last several decades, people had developed better and better chess engines, from the mechanical Turk from the eighteen century, to today with the introduction of Torch. 

Before computers we had today, there was a machine that can beat even the best players, which is called the Turk. The Turk is a machine, secretly operated by a chess master, that looks like it can play by itself. Computers were not able to play by them self until around a century later, when Alan Turing built Turochamp, in 1949, though it never came out of the testing stage. 

Engines never played chess that well until 1983, when Joe Condon made Belle, an engine with a USCF rating of 2250, and was the first the have quiescence search, and a transposition table. Then on 1985, Deep Blue, built by the Carnegie Mellon University, became the first engine to surpass humans in chess, after it beat former World Champion Garry Kasparov in 1997. The engine uses a supercomputer and can evaluate up to 200 million positions per second.  

Garry Kasparov playing against Deep Blue

The 2000s came with accessible chess engines such as ChessMaster or Fritz, or strong ones like Rybka, which won the Computer Chess Championship from 2007 - 2010. Next decade, we have chess engines such as Leela ChessZero, which uses reinforcement learning, Komodo, which uses positional moves, then finding moves with depth. And the best engine, Stockfish, uses advance pruning for maximum depth and sits at a rating of 3200. 

Middle, Date when Introduced, Bottom, Current Rating (2018) *Note, Engines change many times*

You seen the history of chess engines, you can see the strongest ones at the Championship here.

Playing Style + Highlights

If you want to see a great blog about how AlphaZero play, go here

Chess engines have an almost mystical ability to find the right move, no matter how counterintuitive or bizarre it may seem to human players

—  IM Jeremy Silman 

We seen how engines work, and how they evolve over time, but how do they play? Garry Kasparov said that playing Deep Blue feels like playing against an alarm clock but does engines have a style? From Deep Blue, to Alpha Zero, to Stockfish, we will be seeing these interesting games and moves they play. Enjoy!

Stockfish Incredible Sacifices 

We see here in this game between Leela Chess Zero and Stockfish, that Stockfish sacrifices three of their pieces, and got a awesome attack. 

Leela Chess Zero wins with Evan's Gambit

In this game, this time Leela Chess Zero is doing the attack with the Evan's Gambit.