Help For Epaminondas

Introduction

Welcome to the network Epaminondas server. The rules of Epaminondas are below. The commands are the same for all pbmserv games.

Epaminondas is named after the Theban general who invented the phalanx.

Rules of Epaminondas

Setup

Epaminondas is played on a 14x12 board. The two rows closest to each player are filled with pieces of his color.

The board size can be customized in the "challenge" command by using the size option. The syntax is "--size=[rows]x[cols]". For example, the game can also be played on an 8x8 checkboard with this command:

     epaminondas challenge -size=8x8 player1 player2

Movement

The basic unit of movement in Epaminondas is the phalanx. A phalanx is an unbroken line of pieces of the same color in any direction (horizontal, vertical, or diagonal). In the following diagram, the large X in the middle is a part of a 4-piece phalanx vertically, 3-piece plalanxes on both diagonals, and form a phalanx of 1 piece horizontally.

     . . x . . 
     . . x x .
     x . X . .
     . x x x .
     . . . . x

A phalanx may move forward or backward along it length. It may NOT move sideways at all. It may move only as far as its own length, so a phalanx of 3-pieces may move 1, 2, or 3 spaces. It is not necessary to keep existing phalanxes together; a smaller phalanx may break off of a larger one, as long as it does not move more spaces than the number of pieces moved. An isolated piece forms a phalanx of 1, and may move 1 space in any direction.

Capturing

When a phalanx encounters an enemy piece when moving, it may be able to capture one or more enemy pieces. The enemy pieces along the same line as the attacking phalanx will form a phalanx of 1 or more enemy pieces. In order to be able to capture, the attacking phalanx must be longer than the enemy phalanx. If the enemy phalanx is equal in length or longer than the attacking phalanx, it is safe and may not be captured.

When a capture is possible, the leading piece of the attacking phalanx stops on the space occupied by the first enemy piece encountered. That enemy and all other enemy pieces in the defending phalanx are removed from the board. The following diagram illustrate possible captures, and non-captures, by the phalanx of 3 eks.

The ohs are out of range of the eks phalanx:
     . o o . . . x x x .    --->    . o o x x x . . . .

These ohs can be captured:
     . . o o . . x x x .    --->    . . . x x x . . . .

This phalanx of ohs is equal in length and may not be captured:
     . . o o o . x x x .    --->    . . o o o x x x . . 

Only the first phalanx of ohs is captured:
     . o o . o o x x x .    --->    . o o . . x x x . .

Object

The object of the game is to get a piece to the opposite side of the board. But there is an additional complication: after reaching the opposite side of the board, your opponent has one move to counter your threat. There are two ways to do this:

He may capture the piece.
He may move one of his own pieces to your side of the board.

The implications of this is that, at the start of your turn, you have more pieces on the opposite side of the board than your opponent has on your side of the board, you win.

Here is an illustration of what can happen:

     5  x x x . . .
     4  . . x . . .
     3  . . . . o .
     2  . o x . o .
     1  o . . . o .

        A B C D E F

First, Ohs moves e1,e3-e5 to reach the opposite side of the board.

     5  x x x . O .
     4  . . x . O .
     3  . . . . O .
     2  . o x . . .
     1  o . . . . .

        A B C D E F

Eks must get a piece of his own across the board, or capture the piece on E5. He chooses to move C2-D1, so now both players have the same number of pieces across the board.

     5  x x x . o .
     4  . . x . o .
     3  . . . . o .
     2  . o . . . .
     1  o . . X . .

        A B C D E F

Ohs chooses to move E4-D5. He now has two pieces on the opposite side of the board, and again threatens to win if Eks cannot counter him.

     5  x x x O o .
     4  . . x . . .
     3  . . . . o .
     2  . o . . . .
     1  o . . x . .

        A B C D E F

Eks moves A5,C5-D5 which captures both of Ohs pieces, and threatens to win, because he now has more pieces on the opposite side of the board than eks! Ohs has no move to counter the threat, so Eks will win after the next move by Ohs.

     5  . X X X . .
     4  . . x . . .
     3  . . . . o .
     2  . o . . . .
     1  o . . x . .

        A B C D E F

Move Notation

As shown in the preceeding section, the moves sent to the server are notated by giving both end points of the phalanx being moved, followed by the space one end of the phalanx moves to. If a single piece is being moved, simply give the source and destination spaces.