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Queenbee evaluation function for Hex

I created an alpha-beta cutoff search agent for Hex that uses the Queen Bee evaluation function, but I cannot get the function to work properly and need help. The evaluation function is described in section 3.2 of this paper. The function is simple and the explanation is quick to read through.

I have provided my implementation below and have a couple questions:

  1. The function seems to work fine for smaller board sizes, but it cannot be completed quickly for larger boards. What can I do to speed up this calculation?
  2. There is definitely a simple fix for this, but this function is difficult for me to debug and test because there are many recursive calls that I need to walk through. Is there a way to skip all the recursive calls and jump back to the original caller in VS Code?
def qb_distance(state, qb):

    def qb_distance_left(pos, d, v, qb_list):
        r, c = pos[0], pos[1]
        if c == 0: #if the current position is on the left edge of the board, return d
            return d
        if len(qb_list) >= 2:
            qb_list.pop(qb_list.index(min(qb_list)))
            m2 = qb_list.pop(qb_list.index(min(qb_list)))
            if d > m2: #If the distance exceeds the second smallest found, stop searching and return to the caller
                return d
        adjList = [(r,c-1), (r+1, c-1), (r-1, c), (r+1, c), (r-1, c+1), (r, c+1)]
        adjList = [pos for pos in adjList if pos[0] >= 0 and pos[0] < state.size and pos[1] >= 0 and pos[1] < state.size and pos not in v]
        result = []
        visited = [x for x in v]
        visited.append((r,c))
        for pos in adjList:
            if  pos not in state.board:
                result.append(qb_distance_left(pos,d+1,[x for x in visited], [x for x in result]))
            elif state.board.get(pos) == state.player:
                result.append(qb_distance_left(pos,d, [x for x in visited], [x for x in result]))
        result = [x for x in result if x != float("inf")]
        if len(result) < 2:
            return float("inf")
        result.pop(result.index(min(result)))
        return result[result.index(min(result))]

    def qb_distance_right(pos, d, v, qb_list):
        r, c = pos[0], pos[1]
        if c == state.size-1:
            return d
        if len(qb_list) >= 2:
            qb_list.pop(qb_list.index(min(qb_list)))
            m2 = qb_list.pop(qb_list.index(min(qb_list)))
            if d > m2:
                return d
        adjList = [(r-1, c+1), (r, c+1), (r-1, c), (r+1, c), (r,c-1), (r+1, c-1)]
        adjList = [pos for pos in adjList if pos[0] >= 0 and pos[0] < state.size and pos[1] >= 0 and pos[1] < state.size and pos not in v]
        result = []
        visited = [x for x in v]
        visited.append((r,c))
        for pos in adjList:
            if  pos not in state.board:
                result.append(qb_distance_right(pos,d+1,[x for x in visited], [x for x in result]))
            elif state.board.get(pos) == state.player:
                result.append(qb_distance_right(pos,d, [x for x in visited], [x for x in result]))
        result = [x for x in result if x != float("inf")]
        if len(result) < 2:
            return float("inf")
        result.pop(result.index(min(result)))
        return result[result.index(min(result))]

    def qb_distance_top(pos, d, v, qb_list):
        r, c = pos[0], pos[1]
        if r == 0:
            return d
        if len(qb_list) >= 2:
            qb_list.pop(qb_list.index(min(qb_list)))
            m2 = qb_list.pop(qb_list.index(min(qb_list)))
            if d > m2:
                return d
        adjList = [(r-1, c), (r-1,c+1), (r,c-1), (r,c+1), (r+1, c-1), (r+1,c)]
        adjList = [pos for pos in adjList if pos[0] >= 0 and pos[0] < state.size and pos[1] >= 0 and pos[1] < state.size and pos not in v]
        result = []
        visited = [x for x in v]
        visited.append((r,c))
        for pos in adjList:
            if  pos not in state.board:
                result.append(qb_distance_top(pos,d+1,[x for x in visited], [x for x in result]))
            elif state.board.get(pos) == state.player:
                result.append(qb_distance_top(pos,d, [x for x in visited], [x for x in result]))
        result = [x for x in result if x != float("inf")]
        if len(result) < 2:
            return float("inf")
        result.pop(result.index(min(result)))
        return result[result.index(min(result))]

    def qb_distance_bottom(pos, d, v, qb_list):
        r, c = pos[0], pos[1]
        if r == state.size-1:
            return d
        if len(qb_list) >= 2:
            qb_list.pop(qb_list.index(min(qb_list)))
            m2 = qb_list.pop(qb_list.index(min(qb_list)))
            if d > m2:
                return d
        adjList = [(r+1, c-1), (r+1,c), (r,c-1), (r,c+1), (r-1,c), (r-1,c+1)]
        adjList = [pos for pos in adjList if pos[0] >= 0 and pos[0] < state.size and pos[1] >= 0 and pos[1] < state.size and pos not in v]
        result = []
        visited = [x for x in v]
        visited.append((r,c))
        for pos in adjList:
            if  pos not in state.board:
                result.append(qb_distance_bottom(pos,d+1,[x for x in visited], [x for x in result]))
            elif state.board.get(pos) == state.player:
                result.append(qb_distance_bottom(pos,d, [x for x in visited], [x for x in result]))
        result = [x for x in result if x != float("inf")]
        if len(result) < 2:
            return float("inf")
        result.pop(result.index(min(result)))
        return result[result.index(min(result))]
    
    """Get the queen bee distances between the queen bee and all four sides of
       the board. The function handles cases where one or more queen bee distance 
       do not exist (when infinity is returned)."""
    d1, d2 = None, None
    if state.player == 'B':
        d1 = [qb_distance_left(qb, 1, [],[]), qb_distance_right(qb, 1, [],[])]
        d2 = [qb_distance_top(qb,1,[],[]), qb_distance_bottom(qb,1,[],[])]
    elif state.player == 'W':
        d1 = [qb_distance_top(qb,1,[],[]), qb_distance_bottom(qb,1,[],[])]
        d2 = [qb_distance_left(qb, 1, [],[]), qb_distance_right(qb, 1, [],[])]
    if (float("inf") in d1 and float("inf") not in d2) or (float("inf") in d1 and float("inf") in d2):
        return float("-inf")
    elif float("inf") in d2 and float("inf") not in d1:
        return float("inf")
    else:
        d1 = min(d1)
        d2 = min(d2)
        return d2 - d1


source https://stackoverflow.com/questions/77729334/queenbee-evaluation-function-for-hex
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