# masProblem.py - A Multiagent Problem
# AIFCA Python3 code Version 0.8.6 Documentation at http://aipython.org
# Artificial Intelligence: Foundations of Computational Agents
# http://artint.info
# Copyright David L Poole and Alan K Mackworth 2017-2020.
# This work is licensed under a Creative Commons
# Attribution-NonCommercial-ShareAlike 4.0 International License.
# See: http://creativecommons.org/licenses/by-nc-sa/4.0/deed.en
from display import Displayable
class Node(Displayable):
"""A node in a search tree. It has a
name a string
isMax is True if it is a maximizing node, otherwise it is minimizing node
children is the list of children
value is what it evaluates to if it is a leaf.
"""
def __init__(self, name, isMax, value, children):
self.name = name
self.isMax = isMax
self.value = value
self.allchildren = children
def isLeaf(self):
"""returns true of this is a leaf node"""
return self.allchildren is None
def children(self):
"""returns the list of all children."""
return self.allchildren
def evaluate(self):
"""returns the evaluation for this node if it is a leaf"""
return self.value
fig10_5 = Node("a",True,None, [
Node("b",False,None, [
Node("d",True,None, [
Node("h",False,None, [
Node("h1",True,7,None),
Node("h2",True,9,None)]),
Node("i",False,None, [
Node("i1",True,6,None),
Node("i2",True,888,None)])]),
Node("e",True,None, [
Node("j",False,None, [
Node("j1",True,11,None),
Node("j2",True,12,None)]),
Node("k",False,None, [
Node("k1",True,888,None),
Node("k2",True,888,None)])])]),
Node("c",False,None, [
Node("f",True,None, [
Node("l",False,None, [
Node("l1",True,5,None),
Node("l2",True,888,None)]),
Node("m",False,None, [
Node("m1",True,4,None),
Node("m2",True,888,None)])]),
Node("g",True,None, [
Node("n",False,None, [
Node("n1",True,888,None),
Node("n2",True,888,None)]),
Node("o",False,None, [
Node("o1",True,888,None),
Node("o2",True,888,None)])])])])
class Magic_sum(Node):
def __init__(self, xmove=True, last_move=None,
available=[1,2,3,4,5,6,7,8,9], x=[], o=[]):
"""This is a node in the search for the magic-sum game.
xmove is True if the next move belongs to X.
last_move is the number selected in the last move
available is the list of numbers that are available to be chosen
x is the list of numbers already chosen by x
o is the list of numbers already chosen by o
"""
self.isMax = self.xmove = xmove
self.last_move = last_move
self.available = available
self.x = x
self.o = o
self.allchildren = None #computed on demand
lm = str(last_move)
self.name = "start" if not last_move else "o="+lm if xmove else "x="+lm
def children(self):
if self.allchildren is None:
if self.xmove:
self.allchildren = [
Magic_sum(xmove = not self.xmove,
last_move = sel,
available = [e for e in self.available if e is not sel],
x = self.x+[sel],
o = self.o)
for sel in self.available]
else:
self.allchildren = [
Magic_sum(xmove = not self.xmove,
last_move = sel,
available = [e for e in self.available if e is not sel],
x = self.x,
o = self.o+[sel])
for sel in self.available]
return self.allchildren
def isLeaf(self):
"""A leaf has no numbers available or is a win for one of the players.
We only need to check for a win for o if it is currently x's turn,
and only check for a win for x if it is o's turn (otherwise it would
have been a win earlier).
"""
return (self.available == [] or
(sum_to_15(self.last_move,self.o)
if self.xmove
else sum_to_15(self.last_move,self.x)))
def evaluate(self):
if self.xmove and sum_to_15(self.last_move,self.o):
return -1
elif not self.xmove and sum_to_15(self.last_move,self.x):
return 1
else:
return 0
def sum_to_15(last,selected):
"""is true if last, toegether with two other elements of selected sum to 15.
"""
return any(last+a+b == 15
for a in selected if a != last
for b in selected if b != last and b != a)