Sandilya Bhamidipati

How to hide the elephant- or the donkey- in the room: Practical privacy against statistical inference for large data

We propose a practical methodology to protect a users private data, when he wishes to publicly release data that is correlated with his private data, in the hope of getting some utility. Our approach relies on a general statistical inference framework that captures the privacy threat under inference attacks, given utility constraints. Under this framework, data is distorted before it is released, according to a privacy-preserving probabilistic mapping. This mapping is obtained by solving a convex optimization problem, which minimizes information leakage under a distortion constraint. We address a practical challenge encountered when applying this theoretical framework to real world data: the optimization may become untractable and face scalability issues when data assumes values in large size alphabets, or is high dimensional. Our work makes two major contributions. We first reduce the optimization size by introducing a quantization step, and show how to generate privacy mappings under quantization. Second, we evaluate our method on a dataset showing correlations between political views and TV viewing habits, and demonstrate that good privacy properties can be achieved with limited distortion so as not to undermine the original purpose of the publicly released data, e.g. recommendations.

Managing Your Private and Public Data: Bringing Down Inference Attacks Against Your Privacy

We propose a practical methodology to protect a users private data, when he wishes to publicly release data that is correlated with his private data, to get some utility. Our approach relies on a general statistical inference framework that captures the privacy threat under inference attacks, given utility constraints. Under this framework, data is distorted before it is released, according to a probabilistic privacy mapping. This mapping is obtained by solving a convex optimization problem, which minimizes information leakage under a distortion constraint. We address practical challenges encountered when applying this theoretical framework to real world data. On one hand, the design of optimal privacy mappings requires knowledge of the prior distribution linking private data and data to be released, which is often unavailable in practice. On the other hand, the optimization may become untractable when data assumes values in large size alphabets, or is high dimensional. Our work makes three major contributions. First, we provide bounds on the impact of a mismatched prior on the privacy-utility tradeoff. Second, we show how to reduce the optimization size by introducing a quantization step, and how to generate privacy mappings under quantization. Third, we evaluate our method on two datasets, including a new dataset that we collected, showing correlations between political convictions and TV viewing habits. We demonstrate that good privacy properties can be achieved with limited distortion so as not to undermine the original purpose of the publicly released data, e.g., recommendations.

Efficient wikipedia-based semantic interpreter by exploiting top-k processing

Proper representation of the meaning of texts is crucial to enhancing many data mining and information retrieval tasks, including clustering, computing semantic relatedness between texts, and searching. Representing of texts in the concept space derived from Wikipedia has received growing attention recently, due to its comprehensiveness and expertise, This concept-based representation is capable of extracting semantic relatedness between texts that cannot be deduced with the bag of words model. A key obstacle, however, for using Wikipedia as a semantic interpreter is that the sheer size of the concepts derived from Wikipedia makes it hard to efficiently map texts into concept-space. In this paper, we develop an efficient algorithm which is able to represent the meaning of a text by using the concepts that best match it. In particular, our approach first computes the approximate top-k concepts that are most relevant to the given text. We then leverage these concepts for representing the meaning of the given text. The experimental results show that the proposed technique provides significant gains in execution time over current solutions to the problem.

From VFX project management to predictive forecasting

VFX production companies are currently challenged by the increasing complexity of visual effects shots combined with constant schedule demands. The ability to execute in an efficient and cost-effective manner requires extensive coordination between different sites, different departments, and different artists. This coordination demands data-intensive analysis of VFX workflows beyond standard project management practices and existing tools. In this paper, we propose a novel solution centered around a general evaluation data model and APIs that convert production data (job/scene/shot/schedule/task) to business intelligence insights enabling performance analytics and generation of data summarization for process controlling. These analytics provide an impact measuring framework for analyzing performance over time, with the introduction of new production technologies, and across separate jobs. Finally, we show how the historical production data can be used to create predictive analytics for the accurate forecasting of future VFX production process performance.