Incremental slot filling and negation

Building Chatbots in Python

Alan Nichol

Co-founder and CTO, Rasa

Incremental filters

Basic memory

def respond(message, params):
   # update params with entities in message
   # run query
   # pick response
   return response, params

# initialise params
params = {}

# message comes in
response, params = respond(message, params)

Negation

"where should I go for dinner?"

"no I don't like sushi"

"what about Sally's Sushi Place?"

"ok, what about Joe's Steakhouse?"

Negated entities

assume that "not" or "n't" just before an entity means user wants to exclude this
normal entities in green, negated entities in purple

Catching negations

doc = nlp('not sushi, maybe pizza?')

indices = [1, 4]

ents, negated_ents = [], []

start = 0
for i in indices:
     phrase = "{}".format(doc[start:i])
     if "not" in phrase or "n't" in phrase:
        negated_ents.append(doc[i])
     else:
         ents.append(doc[i])
     start = i

Let's practice!

Building Chatbots in Python