Question

I want to build a bot that asks someone a few simple questions and branches based on the answer. I realize parsing meaning from the human responses will be challenging, but how do you setup the program to deal with the ‘state’ of the conversation?

It will be a one-to-one conversation between a human and the bot.

Answer 1

You probably want to look into Markov Chains as the basics for the bot AI. I wrote something a long time ago (the code to which I’m not proud of at all, and needs some mods to run on Python > 1.5) that may be a useful starting place for you: http://sourceforge.net/projects/benzo/

EDIT: Here’s a minimal example in Python of a Markov Chain that accepts input from stdin and outputs text based on the probabilities of words succeeding one another in the input. It’s optimized for IRC-style chat logs, but running any decent-sized text through it should demonstrate the concepts:

import random, sys  NONWORD = '\n' STARTKEY = NONWORD, NONWORD MAXGEN=1000  class MarkovChainer(object):     def __init__(self):         self.state = dict()      def input(self, input):         word1, word2 = STARTKEY         for word3 in input.split():             self.state.setdefault((word1, word2), list()).append(word3)             word1, word2 = word2, word3          self.state.setdefault((word1, word2), list()).append(NONWORD)      def output(self):         output = list()         word1, word2 = STARTKEY         for i in range(MAXGEN):             word3 = random.choice(self.state[(word1,word2)])             if word3 == NONWORD: break             output.append(word3)             word1, word2 = word2, word3         return ' '.join(output)  if __name__ == '__main__':     c = MarkovChainer()     c.input(sys.stdin.read())     print c.output() 

It’s pretty easy from here to plug in persistence and an IRC library and have the basis of the type of bot you’re talking about.