六子棋-人机双人大对决 1.3

This review provides an overview of Liuziqi, a traditional folk board game originating from China. The game is designed for two players, each controlling six pieces, hence the name Liuziqi or Six-Child Chess. The game is played on a 3x3 grid, with the pieces distinguishable by players solely through their form.

Modern variants, also known as Lianliuqi or Connecting Six, have been developed to address certain limitations found in Gomoku and Renju rules, particularly the issue of "first-move always winning" and the complexity of international chess regulations.

The rules include three main capture mechanisms:

• Gunshot: If a player moves two of their pieces adjacent to each other and one of their opponent's pieces is directly next to this pair, the opponent's piece can be captured (referred to as "Gunshot").
• Lift: When a player encloses an opponent's piece between two of their own, they can capture that piece (called "Lift").
• Probing: A player inserts one of their pieces between two of the opponent's adjacent pieces, capturing both (known as "Probing").

Key characteristics of Liuziqi include:

1. Fairness: In principle, like many complex games such as Go and Chess, absolute fairness is challenging. However, in Liuziqi, each move involving two pieces inherently gives the acting player an advantage of one additional piece compared to their opponent. This naturally promotes a balanced gameplay by preventing dominant positions. Compared to Gomoku, Liuziqi presents a more equitable playing field.
2. Complexity: Because fairness is maintained through symmetrical moves, the game allows for arbitrarily large or even infinite boards. Using a 19x19 board as an example, the state space complexity reaches approximately 10^172, comparable to that of Go. The game tree complexity can reach around 10^140, vastly exceeding that of Gomoku.