Justifying Recommendations using
Distantly-Labeled Reviews and FineGrained Aspects
Jianmo Ni, Jiacheng Li, Julian McAuley
Email: jin018@ucsd.edu

Explainability
have:

want:

"Machine washable,
all natural fabrics,
true to size"• Generate explanations of recommendations
that focus on aspects a user cares about

Existing methods• Template-based•••

Determine important features and fill in templates
Ex1: Alice and 7 of your friend like this.
Ex2: You might be interested in documentary, on which this item performs well.

• Retrieval-based••Select the relevant sentences from history reviews
Ex: I agree with several others that this is a good companion to the movie.

• Generation-based••

Generate reviews/tips as explanations
Ex: This is a very good movie.

What are the challenges?
• Training data might not be appropriate• Model needs more controllability and diversity🙂🙂

Building a justification dataset
Can we automatically extract good justifications from data?
Review 1:
First time trying this place out and I was kinda disappointed especially due
to the great reviews this place has.. The sushi was pretty good and theramen was ok... it could be better, i felt as though it was kinda bland.

Building a justification dataset
Can we automatically extract good justifications from data?
Review 1:
First time trying this place out and I was kinda disappointed especially due
to the great reviews this place has.. The sushi was pretty good and theramen was ok... it could be better, i felt as though it was kinda bland.

Dataset annotation
Reviews

Elementary Discourse Units (EDUs)First time trying this place out and I was kinda
disappointed especially due to the great reviews thisplace has.. The sushi was pretty good and the ramen
was ok...

First time trying this place out
and I was kinda disappointed especially
due to the great reviews this place has..
The sushi was pretty good
and the ramen was ok...

BreakDataset annotation
Reviews

Elementary Discourse Units (EDUs)First time trying this place out and I was kinda
disappointed especially due to the great reviews thisplace has.. The sushi was pretty good and the ramen
was ok...

First time trying this place out
and I was kinda disappointed especially
due to the great reviews this place has..
The sushi was pretty good
and the ramen was ok...

BreakFilter
First time trying this place out
due to the great reviews this place has..
The sushi was pretty good
and the ramen was ok...

Dataset annotation
Reviews

Elementary Discourse Units (EDUs)First time trying this place out and I was kinda
disappointed especially due to the great reviews thisplace has.. The sushi was pretty good and the ramen
was ok...

First time trying this place out
and I was kinda disappointed especiallydue to the great reviews this place has..
The sushi was pretty good
and the ramen was ok...

BreakFilter
First time trying this place out
due to the great reviews this place has..
The sushi was pretty good
and the ramen was ok...

LabelFirst time trying this place out
due to the great reviews this place has..
The sushi was pretty good
and the ramen was ok...

Dataset annotation
Reviews

Elementary Discourse Units (EDUs)First time trying this place out and I was kinda
disappointed especially due to the great reviews thisplace has.. The sushi was pretty good and the ramen
was ok...

First time trying this place out
and I was kinda disappointed especially
due to the great reviews this place has..
The sushi was pretty good
and the ramen was ok...

Break

Annotators label 2000 EDUs (kappa = 0.927)
First time trying this place out
due to the great reviews this place has..
The sushi was pretty good
and the ramen was ok...

FilterLabelFirst time trying this place out
due to the great reviews this place has..
The sushi was pretty good
and the ramen was ok...

Dataset expansion
Train off-the shelf classifiers on the small annotated dataset

BERT trained for Sentiment
AnalysisAspect extraction
The tuna is pretty amazing
Appetizers and pasta are excellent here
Great shirt, especially for the price
The quality of the material is greatAspect extraction
The tuna is pretty amazingtuna

Appetizers and pasta are excellent here

appetizers, pasta

Great shirt, especially for the priceshirt, price

The quality of the material is great

quality, material

Conditional generation
How to leverage previous user textual interactions?

User profile
Great burgers but amazing salads here
Best croissant sandwich ever ! ! !
Staff is super friendly and very informative .

This place has some of thebest burgers!

P(justification | user_history, item history)

Generation model

Plan-and-write framework

Historical justifications forthis user and item

Aspect profile for thisuser's justifications

Seq2Seq architectureDecoding strategies
Compare different strategies and the impact of generation
diversity• Beam search• Top-k samplingAspect conditional masked language model
Fine-tuned BERT on domain-specific text where aspect terms
are masked (at a higher rate than other tokens)
Projection Layer

P(atmosphere)

P(service)atmosphere andservice

aretopnotch

𝐶𝐶𝑇𝑇 1𝑇𝑇 2𝑇𝑇 3BERT𝑇𝑇 4𝑇𝑇 5𝑇𝑇 6

𝐸𝐸 𝐶𝐶𝐶𝐶𝐶𝐶

𝐸𝐸1

𝐸𝐸 2

𝐸𝐸 3

𝐸𝐸 4

𝐸𝐸 5

𝐸𝐸 6

Attention Layer
Embedding Layer
Fine-grained Aspects′𝐴𝐴𝑢𝑢𝑢𝑢 = [𝐴𝐴1𝑢𝑢𝑢𝑢 , … , 𝐴𝐴𝑘𝑘𝑢𝑢𝑖𝑖 ][CLS][MASK]

and[MASK]

aretopnotch

Sampling
Start from an aspect-masked historical justification,
repeatedly mask on token and sample, until convergence
IterationIter 0Iter 5
Iter 10Iter 15
Iter 20

Generated sentence
universe [MASK] is extremely friendly and persona ##ble
the [MASK] is extremely friendly and persona ##ble
the [MASK] is extremely friendly and persona ##ble
the staff are extremely cool and persona ##ble
the staff are extra kind , persona ##bleDatasets

Dataset

Train

Dev

Test

# of users# of items# ofaspects

Yelp

1.220 M

115.9 K

115.9 K

115.9 K

51.9 K

2,041

AmazonElectronics

0.202 M

57.9 K

57.9 K

57.9 K

59.0 K581

Automatic evaluation• Trade-off between BLEU and Distinct metricSome examples
Model

Shake Shack

Teharu Sushi

Ground Truth

The burger was good

The rolls are pretty great , typical rolls not thatmany specials

A great burger and fries.

Sushi ?

Lex Rank

Short

Ref2Seq (Review)

i love trader joe ’s , i love trader joe ’sLong but general
the food was good and the service was greatSome examples
Model

Shake Shack

Teharu Sushi

Ground Truth

The burger was good

The rolls are pretty great , typical rolls not thatmany specials

Lex Rank

A great burger and fries.

Sushi ?

Ref2Seq (Review)

i love trader joe ’s , i love trader joe ’s

the food was good and the service was great

Ref2Seq

this place has some of the best burgers

the sushi is delicious

Some examples
Model

Shake Shack

Teharu Sushi

Ground Truth

The burger was good

The rolls are pretty great , typical rolls not thatmany specials

Lex Rank

A great burger and fries.

Sushi ?

Ref2Seq (Review)

i love trader joe ’s , i love trader joe ’s

the food was good and the service was great

Ref2Seq

this place has some of the best burgers

the sushi is deliciousRef2Seq (Top K)

the fries are amazing

fresh and delicious sushi

ACMLM

breakfast sandwiches are overall very filling

overall fun experience with half price sushi

Thanks!
• Email: jin018@ucsd.edu• Dataset and Codehttps://github.com/nijianmo/recsys_justification• We have released a new Amazon Review Dataset (2018)!!!
https://nijianmo.github.io/amazon/index.html