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Inferring	User	Tasks	and	Needs
Rishabh	Mehrotra1,	Emine	Yilmaz2,	Ahmed	Hassan	Awadallah3
1Spotify,	London
2University	College	London
3Microsoft	Research
Outline	of	the	Tutorial
 Section	1:	Introduction
 Section	2:	Characterizing	Tasks
 Section	3:	Tasks	Extraction	Algorithms
 Section	4:	Task	based	Evaluation
 Section	5:	Applications
Section	5:	Applications
 Task	based	personalization
Task	based	recommendations
Task	Tours
Predicting	Task	Continuation
Task	Completion	Dialogue	Systems
Task	Based	Personalization
 Users	tend	to	be	interested	in	certain	tasks	when	they	use	
search	engines
 Represent	users	in	terms	of	tasks	they	are	interested	in
 Personalize	search	results	based	on	that
 Query	recommendation,	re-ranking	search	results,
Traditional	Approach:	Topic	Based	Personalization
 Topics	commonly	
constructed	in	two	ways
 Manual	topical	
categories	(e.g.	ODP)
 Topic	Modelling	Based	
(e.g.	LDA)
Topics
Personalization:	Topics	versus	Tasks
Topics Tasks
Finance,	
Basketball,	Jazz
Finance,	
Basketball,	Pop	
music
Basketball,	Pop	
music
Task	based	Personalization	
[Mehrotra	and	Yilmaz,	ACM	RecSys Posters	14]
 Given	N	users	and	M	tasks
 Construct	an	NxM user-task	association	matrix	R
 Cosine	similarity	between	user	profiles	and	task	representations
 Find	the	Nxd user	feature	matrix	U,	and	Mxd task	feature	matrix	
T s.t.
R 	U	TT
 Discover	the	d	latent	features	underlying	the	interactions	
between	users	and	tasks
Representing	Users	in	the	Task-space
 Existing	user	modeling	methods	fail	to	differentiate	between	
users	having	similar	topical	interests
 User	curious	about	"search	engines"	and	an	experienced	IR	researcher
 a	stockbroker	and	a	normal	investor
 The	objective	is	to	leverage	user's	topical	interest	profiles	
along	with	user's	task	associations.
Topics Tasks
Finance,	
Basketball,	Jazz
Finance,	
Basketball,	Pop	
music
Basketball,	Pop	
music
Coupling	Topics	and	Tasks
[Mehrotra	and	Yilmaz,	ACM	ICTIR15]
 Construct	a	3-mode	tensor	to	jointly	model	the	user's	topical	
and	task	preferences:
 <users,	topics,	tasks>
 Define	each	tensor	component	as:
 A	user's	participation	in	a	certain	task	gets	weighted	by	her	
topical	affinity.
Coupling	Topics	and	Tasks
[Mehrotra	and	Yilmaz,	ACM	ICTIR15]
 Tensor	decomposition	to	leverage	connections	between	different	
users	across	different	topics	and	different	tasks	
 PARAFAC	Tensor	Decomposition	[Stegeman and	Sidiropolous,	Linear	Algebra	and	
Applications,	07]
 Ui,	Vj,	Tk are	D-dimensional	vectors	representing	users,	topics,	and	
tasks,	respectively
 Discover	the	D	latent	features	underlying	the	interactions	between	users,	topics	and	tasks
Coupling	Topics	and	Tasks
[Mehrotra	and	Yilmaz,	ACM	ICTIR15]
Evaluation:	Collaborative	Query	Recommendation
 Identify	user	cohorts	based	on	user	
preferences	
 Personalize	search	results	based	on	
recommendations	from	similar	users
Number	of	Similar	Users
Section	5:	Applications
 Task	based	personalization
Task	based	recommendations
Task	Tours
Predicting	Task	Continuation
Task	Completion	Dialogue	Systems
 Provide	heterogeneous	recommendations	during	users	
browsing	process
 Define	tasks	as	demand	sequences	embedded	in	user	browsing	
sessions
Task-based	Recommendation	on	a	Web-Scale
 Step	1:	Collaborative	Task	Mining:
 extract	frequent	demand	sequences	from	large	scale	browser	logs
 achieved	via	frequent	sequence	mining	problem
 Step	2:	Task-based	Demand	Prediction
 predict	the	upcoming	demand	of	a	user	given	the	current	browsing	session
 estimate	the	probability	of	each	demand	d	 D	being	the	follow-on	demand	of	
the	current	session
 Step	3:	Task-based	Recommendation
 Provide	site-level	recommendations	(based	on	predicted	demands)
 Provide	link-level	recommendations	(heterogeneous	recommendations	
based	on	browsing	behavior)
Task-based	Recommendation	on	a	Web-Scale
Task	Tours:	Helping	Users	Tackle	Complex	Search	Tasks	
Automatically	create	multi-step	task	tours:
 URL	labeling	with	topical	category	to	identify	tasks
 construction	of	the	task	graph	that	relates	tasks	to	
each	other
 building	of	the	tours	using	task	graph
 identification	of	triggers	
Task	tours	help	users:
 understand	the	required	steps	to	complete	a	task,
 find	URLs	related	to	the	active	task
 alert	users	to	activities	they	may	have	missed
Task	Tours:	Helping	Users	Tackle	Complex	Search	Tasks,	CIKM	2012
Predicting	Task	Continuation
 Understand,	characterize	and	
detect	tasks	which	will	be	
continued
 Bing	logs	used	to	identify	intent,	
topics	&	search	behavior	
associated	with	long	running	
tasks
 Prediction	model	using	various	
features
Search,	Interrupted:	Understanding	and	Predicting	Search	Task	Continuation;	SIGIR	2012
Task	continuation	for	broad	search	intent
Task	Completion	Dialogue	Systems
 Reinforcement	learning	based	
model
 Goal	directed	conversations
 Accesses	external	knowledge	
base
 Slot	filling	to	form	a	semantic	
frame
End-to-End	Task-Completion	Neural	Dialogue	Systems,	arXiv 2017
Section	5:	Applications
 Task	based	personalization
Task	based	recommendations
Task	Tours
Predicting	Task	Continuation
Task	Completion	Dialogue	Systems
Summary	- I
 Query	intent	understanding
 Classification	based	(ODP,	LDA)
 Cluster	based	(Random	walks,	reformulations)
 Session	based	techniques
 Time	based	segmentation
 Content	based	segmentation
 Hybrid	segmentation
 Extracting	search	tasks
 Evaluating	task	extraction	algorithms
 Applications
 Query	intent	understanding
 Extracting	search	tasks
 Task	Extraction
 Clustering	based	approaches
 Entity	oriented	task	extraction
 Structured	SVM	based	bestlinks structures
 LDA	topics	with	Hawkes	process
 Tasks	 Subtasks
 dd-CRP	with	embeddings model
 BRT	Hierarchical	Subtask	segmentation
 Evaluating	task	extraction	algorithms
 Applications
Summary	- II
 Query	intent	understanding
 Extracting	search	tasks
 Evaluating	task	extraction	algorithms
 Gold	standard	dataset
 User	study	based	evaluation
 Alternative	techniques
 TREC	Tasks	Tracks
 Applications
Summary	- III
Query	intent	understanding
Extracting	search	tasks
Evaluating	task	extraction	algorithms
Applications
 Task	based	user	modeling
 Related	Search	suggestions
 Task	based	ecommerce	recommendations
Summary	- IV
Ongoing/Future	Work
 Task	based	user	satisfaction	prediction
 Digital	assistants
 Task	understanding
 Task	completion
 Book	Uber
 Deliver	food
 Task	based	recommendations
 Beyond	search	 web	tasks
Questions?
 Rishabh	Mehrotra
Research	Scientist
Spotify,	London
rishabhm@spotify.com
 Emine	Yilmaz
Associate	Professor,	UCL
Faculty	Fellow,	The	Alan	Turing	Institute
Research	Consultant,	Microsoft	Research
emine.yilmaz@ucl.ac.uk
 Ahmed	Hassan	Awadallah
Research	Lead
Microsoft	Research,	Redmond
hassanam@microsoft.com
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Deadline: 30th November 2017
Notification: 15th December 2017
Workshop: 9th February 2018
aka.ms/wsdm2018-learnir-workshop

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