Computer Science Colloquium
Time+Place : Tuesday 01/05/2012 14:30 room 337-8 Taub  Bld.
Speaker    : Yossi Gil
Affiliation: Computer Science, Technion
Title      : How Do Classes Choose Their Parents?
             (Preferential Attachment to the Trial)
Abstract   :
Previous research repeatedly discovered a power-law distribution  of
object-oriented software metrics. The classical process of preferential
attachment was proposed as a possible explanation. In this presentation, I
will describe research in progress which tries to evaluate this conjecture:
we focus on the famous Number of Children (NOC) object-oriented software
metric, that is, the number of immediate sub-classes a given class has. We
examine the history of development of several software artifacts in attempt
to asses hypothesis underlying preferential attachment,  namely that the
number of existing children a class already has, determines the probability
it is selected as a parent again. Each history is converted to a large
system of high-degree polynomial equations whose solution provides the
desired probabilities. We describe a numerical method for solving this
system, and employing it, we are able to reason about dependencies. Our
finding give empirical support for the preferential attachment hypothesis.
However we identify  a number of equal or better  predictors of this
probability, including the class's age, i.e.,  how recently it was changed.
The strongest and unequivocal predictor turns out to  be the total number of
changes the class went through.
Work carried out in cooperation with Sabih Agbaria, Irad Yavneh and Amnon J.
Short Bio:
Yossi Gil is is on the faculty of the department of computer science at the
Refreshments served from 14:15 on,
 	Lecture starts at 14:30
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