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CS223 CreditGraphs

CS223: Efficient Algorithms for Detecting & Classifying Credit Communities

Final project for Harvard CS 223 fall 2019 (probabilistic analysis of algorithms)

File listing:

  • my_graphs.py is where the graphs we're working with are defined; we hold them constant, but the code to generate new graphs is present in this file as well
  • alg.py is where we implement discovery algorithm
  • eigen.py is where we implement eigentrust algorithm
  • A copy of our final report is located in the pdf in the home directory

Graphs

Our two sample graphs are:

  • 30 nodes each
  • G_COMPLETE is made of three complete graphs (10 nodes each), then we manually connect two nodes between each of the subgraphs (for 6 total added edges) to connect them
  • G_BIPARTITE is constructed similarly, we create three separate subgraphs(they are actually identical due to the identical random seed), and add edges to connect the three. But to simulate a more interesting graph, subgraph1 to 2 is only connected by one edge. While subgraph 2 to 3, and 3 to 1, are connected by three edges.
  • We also have the subgraphs used to implement the above, as individual subgraphs not connected to each other; however these are actually defined directly in alg1.py and eigen.py for our final project results

Usage:

The code is very simple. To run it for our three comparison

``` 
$ python alg1.py
$ python eigen.py
```

To run it for each of the graphs above, change

  • G_COMPLETE to G_BIPARTITE
  • or for the subgraphs, change the flags subgraphs_complete or subgraphs_bipartite

The data is written out to a data.csv file (warning, it's overwritten each time -- we manually copied our data into a separate spreadsheet for analysis).

The rows are our parameter:

pCW .5, pinit .1, cond .8/.2
pCW .8, pinit .1, cond .8/.2
pCW .95, pinit .1, cond .8/.2
pCW .5, pinit .2, cond .8/.2
pCW .8, pinit .2, cond .8/.2
pCW .95, pinit .2, cond .8/.2
pCW .5, pinit .1, cond .95/.05
pCW .8, pinit .1, cond .95/.05
pCW .95, pinit .1, cond .95/.05
pCW .5, pinit .2, cond .95/.05
pCW .8, pinit .2, cond .95/.05
pCW .95, pinit .2, cond .95/.05

where pCW indicates the probability a node is creditworthy, pinit indicates the probability a creditworthy node will be in our initial recommenders list, and cond indicates the probability a neighbor is recommended in the true positive and false positive cases.

The columns are our four metrics:

COST	False positive rate	Pct Creditworthy Borrowers Disovered	Number of Rounds to Convergence

where false positive rate indicates the number of people we lent to, who turned out not to be crediworthy, over all people who are creditworthy

Credits

Nao Ouyang, Juspreet Singh Sandhu, Mark York Dec 2019