Updated introduction and made it more concise

Signed-off-by: Jim Martens <github@2martens.de>
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Jim Martens 2019-08-01 14:15:17 +02:00
parent 4fbe894527
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1 changed files with 17 additions and 31 deletions

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@ -8,34 +8,21 @@ Famous examples like the automatic soap dispenser which does not
recognize the hand of a black person but dispenses soap when presented
with a paper towel raise the question of bias in computer
systems~\cite{Friedman1996}. Related to this ethical question regarding
the design of so called algorithms, a term often used in public
discourse for applied neural networks, is the question of
the design of so called algorithms is the question of
algorithmic accountability~\cite{Diakopoulos2014}.
The charm of supervised neural networks, that they can learn from
input-output relations and figure out by themselves what connections
are necessary for that, is also their Achilles heel. This feature
makes them effectively black boxes. It is possible to question the
training environment, like potential biases inside the data sets, or
the engineers constructing the networks but it is not really possible
to question the internal calculations made by a network. On the one
hand, one might argue, it is only math and nothing magical that
happens inside these networks. Clearly it is possible, albeit a chore,
to manually follow the calculations of any given trained network.
After all it is executed on a computer and at the lowest level only
uses basic math that does not differ between humans and computers. On
the other hand not everyone is capable of doing so and more
importantly it does not reveal any answers to questions of causality.
Supervised neural networks learn from input-output relations and
figure out by themselves what connections are necessary for that.
This feature is also their Achilles heel: it makes them effectively
black boxes and prevents any answers to questions of causality.
However, these questions of causility are of enormous consequence when
neural networks are used, for example, in predictive policing. Is a
correlation, a coincidence, enough to bring forth negative consequences
results of neural networks are used to make life changing decisions:
Is a correlation enough to bring forth negative consequences
for a particular person? And if so, what is the possible defence
against math? Similar questions can be raised when looking at computer
vision networks that might be used together with so called smart
CCTV cameras, for example, like those tested at the train station
Berlin Südkreuz. What if a network implies you committed suspicious
behaviour?
CCTV cameras to discover suspicious activity.
This leads to the need for neural networks to explain their results.
Such an explanation must come from the network or an attached piece
@ -103,17 +90,17 @@ representation of the input and has to find a decompression
that reconstructs the input as accurate as possible. During
training these auto-encoders learn to reproduce a certain group
of object classes. The actual novelty detection takes place
during testing. Given an image, and the output and loss of the
during testing: Given an image, and the output and loss of the
auto-encoder, a novelty score is calculated. A low novelty
score signals a known object. The opposite is true for a high
novelty score.
\subsection*{Research Question}
Given these two approaches to solve the explanation task of above,
it comes down to performance. At the end of the day the best
theoretical idea does not help in solving the task if it cannot
be implemented in a performant way. Miller et al. have shown
Both presented approaches describe one way to solve the aforementioned
problem of explanation. They can be differentiated by measuring
their performance: the best theoretical idea is useless if it does
not perform well. Miller et al. have shown
some success in using dropout sampling. However, the many forward
passes during testing for every image seem computationally expensive.
In comparison a single run through a trained auto-encoder seems
@ -124,11 +111,10 @@ use the work of Miller et al. as baseline to compare against.
They use the SSD~\cite{Liu2016} network for object detection,
modified by added dropout layers, and the SceneNet
RGB-D~\cite{McCormac2017} data set using the MS COCO~\cite{Lin2014}
classes. Instead of dropout sampling my approach will use
an auto-encoder for novelty detection with all else, like
using SSD for object detection and the SceneNet RGB-D data set,
being equal. With respect to auto-encoders a recent implementation
of an adversarial auto-encoder~\cite{Pidhorskyi2018} will be used.
classes. I will use a simple implementation of an auto-encoder and
novelty detection to compare with the work of Miller et al.
SSD for the object detection and SceneNet RGB-D as the data
set are used for both approaches.
\paragraph{Hypothesis} Novelty detection using auto-encoders
delivers similar or better object detection performance under open set