/**
 * Count how many 'live' neighbors are at a given cell (i,j).
 *
 * @param i, j two integers giving the coordinates of the cell
 *
 * @return the number of living cells among the eight neighbors as 
 *         an integer
 */
    private int livingNeighbors(int i, int j) {

        int result = 0;
        if (isAlive(i-1, j-1)) result++;
        if (isAlive(i-1, j)) result++;
        if (isAlive(i-1, j+1)) result++;
        if (isAlive(i, j-1)) result++;
        if (isAlive(i, j+1)) result++;
        if (isAlive(i+1, j-1)) result++;
        if (isAlive(i+1, j)) result++;
        if (isAlive(i+1, j+1)) result++;
        return result;
    }

/**
 * Determine if a cell is live. Here we assume the board is represented
 * by a 2-D boolean array. If the cell holds a value 'true', the cell
 * is live; otherwise the cell is dead.
 *
 * @param i, j two integers giving the coordinates of the cell
 *
 * @return true if the cell is live, false otherwise
 */
    private boolean isAlive(int i, int j) {
        if (i >= 0 && i < mWorld.length &&
	    j >= 0 && j < mWorld[i].length && 
	    mWorld[i][j])
	    return true;
        else
	    return false;

    }