graphs (by @cdixon and @hunch)

8/7/2019 graphs (by @cdixon and @hunch)

http://slidepdf.com/reader/full/graphs-by-cdixon-and-hunch 1/36

Hashtag: #hunchgraphs



Malcolm Gladwell Title:

What Chipotle, Glenn Beck and

Alien Abductions Teach Us About

the Future of the Web



Graphs 101

A BNodeNode

Edge

Social networks (Facebook): nodes are people, edges “friendship”

Communication graph (Skype): nodes are people, edges communications

Taste graph (Hunch): nodes are people, edges taste similarity

Search ranking graph (Google): nodes are pages, edges links

Interest graph (Twitter, Instagram): nodes are people, edges interest



First Graph Theory:Euler’s 7 bridges of Koeningsberg

•Convert land to nodes & bridges to edges•Any node that is passed through must haveeven number of edges•Thus only solvable if you have 0 or 2 nodeswith odd number of edges

•Is it possible to traverse the town & crosseach bridge exactly once?



Undirected Graph: Relationship Symmetric(Friendship)



Directed Graph: Relationship Non-symmetric(Like, follow, subscribe)

One could argue that Twitter’s main innovation was making edges non-

symmetric (directed), turned social network into publishing platform

Facebook began as undirected friend graph but has since bolted directed“like” graph on top of it.



Interlude: data fun



Averages

Twitter :

Number of followers: 62.97 per user Number of followees: 43.52 per user

Facebook:Number of facebook likes: 217.2 per item (liked)Number of facebook likes: 29.30 per user

But distributions are interestingly different...



Twitter distributions are power curves

Spike of “# following” curve around 20 due to old onboarding process (?)

Distribution of # of followers you have Distribution of # of people you follow



Facebook friends is more like a bell curve

y = number of people; x = number of friends for those people



Facebook “likes” similar to Twitter (sincealso non-symmetric?)



Some real world applications



Marketing

Telecom company tested using phone call graph to use for direct mail*

Targeting network neighbors of purchasers dominated other targeting techniques.

Today, Facebook and many ad networks use similar targeting for online ads.

* “Network-Based Marketing: IdentifyingLikely Adopters via Consumer Networks - Shawndra Hill, Foster

Provost and Chris Volinsky

AB

purchased product

C

similar demographics to A

communicates with A

B more likely to buy than C



Defense

You can infer organizational hierarchies from communication patterns.

Governments use this to map rogue organizations.

Boss Henchman

A Bcalls

responds immediately

ABcalls

responds slowly

A B

THEREFORE



Google founders’ $200B idea

Words and documents are nodes, connected by occurrence

PageRank: Links are directed graph

Node Node



Gratuitous XKCD comic



Building graphs



Start with smaller graph:Bowling Pin Strategy

H a r v a r d

B o s t o n

a r e a c o l l e g e s

B o s t o n

a r e a c o l l e g e s

M o r e c o l l e g e s

M o r e c o l l e g e s

E v e r y o n e

E

v e r y o n e

• Utility is proportional to square of network coverage, but how to start?• Shrink size of the initial network and grow from there• Also try to choose a sub-network with natural ‘spillover’ effects

•In this example, students at one college tend to have friends at others



Find clusters within existing graphs

A lot of people in the 90s thought dating would be “winner take all” - but didn’t account for clustered graph structure



Introducing Overlap of Buyers/Sellers can addDifferentiation even in Entrenched Graphs

Heterogeneousbuyers/sellers Hybrid

Homogenousbuyers/sellers

For heterogenous buyers/sellers consider “Ladies night strategy”



Graph wars



Facebook vs Google on opening social graphs

Google:



When to Interoperate?

Metcalfe’s Law

Network value ~ (nodes)2

Corollary:

Little guy benefits more than big guy

Little guy joins network and:•Big guy gains small incremental increase in connections•Little guy gains value of the many existing connections

•That’s why AIM (as incumbent big player) resisted whenYahoo! & Google wanted to interoperate for IM

Little guy

Big guy



On the other hand…

• Each little guy benefits more than the big guy from interoperating

• But thousands of little guys relying on the big guy solidifies big guy position

• Facebook realized this and introduced Facebook Apps, Connect and other “interoperating” features to prevent the “social network decay” that destroyed

previous social networks.

Facebook dev platform



Shameless self-promotion: taste graphs



Tastemates as Basis of a Graph

CarcasonneModern Conflict

?

Enigmo

Someone out there must enjoy the same tile/strategy games I do…And chances are they are not (yet, anyway) my friend



The “Cold Start” Challengefor Taste-Based Predictions

How to provide initial recommendations for a new user?

Force train, then predict

Assume tastes are driven by social graph

Leverage cross-vertical knowledge andadjacent known nodes in Taste Graph



One Cold Start Solution:Propagate Known Data to Unknown Nodes

• Iteratively propogate with adjacent data• Dynamically adjust with ‘hard’ data• Lather, rinse, repeat

= Known data

= Unknown data

A li i



Applications

Fun with APIs

“netflix predictions

for everything”

e-commerceand mobile

Youzakk, AutomaticDJ



Since we’re at Google, some more stuff aboutGoogle



Communications Graphs:How Related are they to Social or Taste Graphs?

My iPhone contacts include some of my friends……but also my plumber, doctor, network administrator, UnitedAirlines and the Chinese restaurant around the corner

A lot of people were surprised that their email contacts were

assumed to be active social contacts

Could We Use Ad Preferences to



Could We Use Ad Preferences toCold Start Restaurant Recs?

32

hotpot

+



We know this person likes Classical Music, Yoga, Poetry, and Hiking

33

Hunch would recommend Seafood Mediterranean Greek and Sushi Restaurants



Hunch would recommend Seafood, Mediterranean, Greek, and Sushi Restaurants

Cross domain data can solve the “Napoleon



Cross domain data can solve the NapoleonDynamite” problem

graphs (by @cdixon and @hunch)

Documents