Blog
The latest news from Google AI
SLING: A Natural Language Frame Semantic Parser
Wednesday, November 15, 2017
Posted by Michael Ringgaard, Software Engineer and Rahul Gupta, Research Scientist
Until recently, most practical
natural language understanding
(NLU) systems used a pipeline of analysis stages, from part-of-speech tagging and dependency parsing to steps that computed a semantic representation of the input text. While this facilitated easy modularization of different analysis stages, errors in earlier stages would have cascading effects in later stages and the final representation, and the intermediate stage outputs might not be relevant on their own. For example, a typical pipeline might perform the task of
dependency parsing
in an early stage and the task of coreference resolution towards the end. If one was only interested in the output of
coreference resolution
, it would be affected by cascading effects of any errors during dependency parsing.
Today we are announcing
SLING
, an experimental system for parsing natural language text directly into a representation of its meaning as a
semantic frame graph
. The output frame graph directly captures the semantic annotations of interest to the user, while avoiding the pitfalls of pipelined systems by not running any intermediate stages, additionally preventing unnecessary computation. SLING uses a special-purpose
recurrent neural network
model to compute the output representation of input text through incremental editing operations on the frame graph. The frame graph, in turn, is flexible enough to capture many semantic tasks of interest (more on this below). SLING's parser is trained using only the input words, bypassing the need for producing any intermediate annotations (e.g. dependency parses).
SLING provides fast parsing at inference time by providing (a) an efficient and scalable frame store implementation and (b) a JIT compiler that generates efficient code to execute the recurrent neural network. Although SLING is experimental, it achieves a parsing speed of >2,500 tokens/second on a desktop CPU, thanks to its efficient frame store and neural network compiler. SLING is implemented in C++ and it is available for download on GitHub. The entire system is described in detail in a
technical report
as well.
Frame Semantic Parsing
Frame Semantics [
1
] represents the meaning of text — such as a sentence — as a set of formal statements. Each formal statement is called a
frame
, which can be seen as a unit of knowledge or meaning, that also contains interactions with concepts or other frames typically associated with it. SLING organizes each frame as a list of slots, where each slot has a name (role) and a value which could be a literal or a link to another frame. As an example, consider the sentence:
“Many people now claim to have predicted Black Monday.”
The figure below illustrates SLING recognizing mentions of entities (e.g. people, places, or events), measurements (e.g. dates or distances), and other concepts (e.g. verbs), and placing them in the correct semantic roles for the verbs in the input. The word
predicted
evokes the most dominant sense of the verb "predict", denoted as a PREDICT-01 frame. Additionally, this frame also has interactions (slots) with who made the prediction (denoted via the ARG0 slot, which points to the PERSON frame for
people
) and what was being predicted (denoted via ARG1, which links to the EVENT frame for
Black Monday
). Frame semantic parsing is the task of producing a directed graph of such frames linked through slots.
Although the example above is fairly simple, frame graphs are powerful enough to model a variety of complex semantic annotation tasks. For starters, frames provide a convenient way to bring together language-internal and external information types (e.g. knowledge bases). This can then be used to address complex language understanding problems such as reference, metaphor, metonymy, and perspective. The frame graphs for these tasks only differ in the inventory of frame types, roles, and any linking constraints.
SLING
SLING trains a recurrent neural network by optimizing for the semantic frames of interest.
The internal learned representations in the network’s hidden layers replace the hand-crafted feature combinations and intermediate representations in pipelined systems. Internally, SLING uses an encoder-decoder architecture where each input word is encoded into a vector using simple lexical features like the raw word, its suffix(es), punctuation etc. The decoder uses that representation, along with recurrent features from its own history, to compute a sequence of
transitions
that update the frame graph to obtain the intended frame semantic representation of the input sentence. SLING trains its model using
TensorFlow
and
DRAGNN
.
The animation below shows how frames and roles are incrementally added to the under-construction frame graph using individual transitions. As discussed earlier with our simple example sentence, SLING connects the VERB and EVENT frames using the role ARG1, signifying that the EVENT frame is the concept being predicted. The EVOKE transition evokes a frame of a specified type from the next few tokens in the text (e.g. EVENT from
Black Monday
). Similarly, the CONNECT transition links two existing frames with a specified role. When the input is exhausted and the last transition (denoted as STOP) is executed, the frame graph is deemed as complete and returned to the user, who can inspect the graph to get the semantic meaning behind the sentence.
One key aspect of our transition system is the presence of a small fixed-size attention buffer of frames that represents the most recent frames to be evoked or modified, shown with the orange boxes in the figure above. This buffer captures the intuition that we tend to remember knowledge that was recently evoked, referred to, or enhanced. If a frame is no longer in use, it eventually gets flushed out of this buffer as new frames come into picture. We found this simple mechanism to be surprisingly effective at capturing a large fraction of inter-frame links.
Next Steps
The illustrative experiment above is just a launchpad for research in semantic parsing for tasks such as knowledge extraction, resolving complex references, and dialog understanding. The SLING
release
on Github comes with a pre-trained model for the task we illustrated, as well as examples and recipes to train your own parser on either the supplied synthetic data or your own data. We hope the community finds SLING useful and we look forward to engaging conversations about applying and extending SLING to other semantic parsing tasks.
Acknowledgements
The research described in this post was done by Michael Ringgaard, Rahul Gupta, and Fernando Pereira. We thank the Tensorflow and DRAGNN teams for open-sourcing their packages, and various colleagues at DRAGNN who helped us with multiple aspects of SLING's training setup.
1
Charles J. Fillmore. 1982. Frame semantics. Linguistics in the Morning Calm, pages 111–138.
↩
Labels
accessibility
ACL
ACM
Acoustic Modeling
Adaptive Data Analysis
ads
adsense
adwords
Africa
AI
Algorithms
Android
Android Wear
API
App Engine
App Inventor
April Fools
Art
Audio
Augmented Reality
Australia
Automatic Speech Recognition
Awards
Cantonese
Chemistry
China
Chrome
Cloud Computing
Collaboration
Computational Imaging
Computational Photography
Computer Science
Computer Vision
conference
conferences
Conservation
correlate
Course Builder
crowd-sourcing
CVPR
Data Center
Data Discovery
data science
datasets
Deep Learning
DeepDream
DeepMind
distributed systems
Diversity
Earth Engine
economics
Education
Electronic Commerce and Algorithms
electronics
EMEA
EMNLP
Encryption
entities
Entity Salience
Environment
Europe
Exacycle
Expander
Faculty Institute
Faculty Summit
Flu Trends
Fusion Tables
gamification
Gboard
Gmail
Google Accelerated Science
Google Books
Google Brain
Google Cloud Platform
Google Docs
Google Drive
Google Genomics
Google Maps
Google Photos
Google Play Apps
Google Science Fair
Google Sheets
Google Translate
Google Trips
Google Voice Search
Google+
Government
grants
Graph
Graph Mining
Hardware
HCI
Health
High Dynamic Range Imaging
ICLR
ICML
ICSE
Image Annotation
Image Classification
Image Processing
Inbox
India
Information Retrieval
internationalization
Internet of Things
Interspeech
IPython
Journalism
jsm
jsm2011
K-12
KDD
Keyboard Input
Klingon
Korean
Labs
Linear Optimization
localization
Low-Light Photography
Machine Hearing
Machine Intelligence
Machine Learning
Machine Perception
Machine Translation
Magenta
MapReduce
market algorithms
Market Research
Mixed Reality
ML
MOOC
Moore's Law
Multimodal Learning
NAACL
Natural Language Processing
Natural Language Understanding
Network Management
Networks
Neural Networks
Nexus
Ngram
NIPS
NLP
On-device Learning
open source
operating systems
Optical Character Recognition
optimization
osdi
osdi10
patents
Peer Review
ph.d. fellowship
PhD Fellowship
PhotoScan
Physics
PiLab
Pixel
Policy
Professional Development
Proposals
Public Data Explorer
publication
Publications
Quantum AI
Quantum Computing
renewable energy
Research
Research Awards
resource optimization
Robotics
schema.org
Search
search ads
Security and Privacy
Semantic Models
Semi-supervised Learning
SIGCOMM
SIGMOD
Site Reliability Engineering
Social Networks
Software
Speech
Speech Recognition
statistics
Structured Data
Style Transfer
Supervised Learning
Systems
TensorBoard
TensorFlow
TPU
Translate
trends
TTS
TV
UI
University Relations
UNIX
User Experience
video
Video Analysis
Virtual Reality
Vision Research
Visiting Faculty
Visualization
VLDB
Voice Search
Wiki
wikipedia
WWW
YouTube
Archive
2018
May
Apr
Mar
Feb
Jan
2017
Dec
Nov
Oct
Sep
Aug
Jul
Jun
May
Apr
Mar
Feb
Jan
2016
Dec
Nov
Oct
Sep
Aug
Jul
Jun
May
Apr
Mar
Feb
Jan
2015
Dec
Nov
Oct
Sep
Aug
Jul
Jun
May
Apr
Mar
Feb
Jan
2014
Dec
Nov
Oct
Sep
Aug
Jul
Jun
May
Apr
Mar
Feb
Jan
2013
Dec
Nov
Oct
Sep
Aug
Jul
Jun
May
Apr
Mar
Feb
Jan
2012
Dec
Oct
Sep
Aug
Jul
Jun
May
Apr
Mar
Feb
Jan
2011
Dec
Nov
Sep
Aug
Jul
Jun
May
Apr
Mar
Feb
Jan
2010
Dec
Nov
Oct
Sep
Aug
Jul
Jun
May
Apr
Mar
Feb
Jan
2009
Dec
Nov
Aug
Jul
Jun
May
Apr
Mar
Feb
Jan
2008
Dec
Nov
Oct
Sep
Jul
May
Apr
Mar
Feb
2007
Oct
Sep
Aug
Jul
Jun
Feb
2006
Dec
Nov
Sep
Aug
Jul
Jun
Apr
Mar
Feb
Feed
Google
on
Follow @googleai
Give us feedback in our
Product Forums
.
