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AnimalShogi

Usage

import pgx

env = pgx.make("animal_shogi")

or you can directly load AnimalShogi class

from pgx.animal_shogi import AnimalShogi

env = AnimalShogi()

Description

Animal Shogi (Dōbutsu shōgi) is a variant of shogi primarily developed for children. It consists of a 3x4 board and four types of pieces (five including promoted pieces). One of the rule differences from regular shogi is the Try Rule, where entering the opponent's territory with the king leads to victory.

See also Wikipedia

Specs

Name Value
Version v0
Number of players 2
Number of actions 132
Observation shape (4, 3, 194)
Observation type float
Rewards {-1, 0, 1}

Observation

Index Description
[:, :, 0:5] my pieces on board
[:, :, 5:10] opponent's pieces on board
[:, :, 10:16] my hands
[:, :, 16:22] opponent's hands
[:, :, 22:24] repetitions
... ...
[:, :, 193] player_id's turn'
[:, :, 194] Elapsed timesteps (normalized to 1)

Action

Uses AlphaZero like action label:

  • 132 labels
  • Move: 8 x 12 (direction) x (source square)
  • Drop: 3 x 12 (drop piece type) x (destination square)

Rewards

Non-zero rewards are given only at the terminal states. The reward at terminal state is described in this table:

Reward
Win +1
Lose -1
Draw 0

Termination

Termination happens when

  1. If either player's king is checkmated, or
  2. if either king enters the opponent's territory (farthest rank)
  3. If the same position occurs three times.
  4. If 250 moves have passed (a unique rule in Pgx).

In cases 3 and 4, the game is declared a draw.

Version History

  • v0 : Initial release (v1.0.0)

Baseline models

Pgx offers a baseline model for Animal Shogi. Users can use it for an anchor opponent in evaluation. See our paper for more details. See this colab for how to use it.

Model ID Description
animal_shogi_v0 See our paper for the training details.