Venn predictors and isotonic regression

This note introduces Venn-Abers predictors, a new class of Venn predictors based on the idea of isotonic regression. As all Venn predictors, Venn-Abers predictors are well calibrated under the exchangeability assumption

Detecting adversarial manipulation using inductive Venn-ABERS predictors

Inductive Venn-ABERS predictors (IVAPs) are a type of probabilistic predictors with the theoretical guarantee that their predictions are perfectly calibrated. In this paper, we propose to exploit this calibration property for the detection of adversarial examples in binary classification tasks. By rejecting predictions if the uncertainty of the IVAP is too high, we obtain an algorithm that is both accurate on the original test set and resistant to adversarial examples. This robustness is observed on adversarials for the underlying model as well as adversarials that were generated by taking the IVAP into account. The method appears to offer competitive robustness compared to the state-of-the-art in adversarial defense yet it is computationally much more tractable

Prescience:Probabilistic Guidance on the Retraining Conundrum for Malware Detection

Malware evolves perpetually and relies on increasingly sophisticatedattacks to supersede defense strategies. Datadrivenapproaches to malware detection run the risk of becomingrapidly antiquated. Keeping pace with malwarerequires models that are periodically enriched with freshknowledge, commonly known as retraining. In this work,we propose the use of Venn-Abers predictors for assessingthe quality of binary classification tasks as a first step towardsidentifying antiquated models. One of the key bene-fits behind the use of Venn-Abers predictors is that they areautomatically well calibrated and offer probabilistic guidanceon the identification of nonstationary populations ofmalware. Our framework is agnostic to the underlying classificationalgorithm and can then be used for building betterretraining strategies in the presence of concept drift. Resultsobtained over a timeline-based evaluation with about 90Ksamples show that our framework can identify when modelstend to become obsolete

Computationally efficient versions of conformal predictive distributions

Conformal predictive systems are a recent modification of conformal predictors that output, in regression problems, probability distributions for labels of test observations rather than set predictions. The extra information provided by conformal predictive systems may be useful, e.g., in decision making problems. Conformal predictive systems inherit the relative computational inefficiency of conformal predictors. In this paper we discuss two computationally efficient versions of conformal predictive systems, which we call split conformal predictive systems and cross-conformal predictive systems. The main advantage of split conformal predictive systems is their guaranteed validity, whereas for cross-conformal predictive systems validity only holds empirically and in the absence of excessive randomization. The main advantage of cross-conformal predictive systems is their greater predictive efficiency.Comment: 31 pages, 14 figures, 1 table. The conference version published in the Proceedings of COPA 2018, and the journal version is to appear in Neurocomputin

Calibration of Natural Language Understanding Models with Venn--ABERS Predictors

Transformers, currently the state-of-the-art in natural language understanding (NLU) tasks, are prone to generate uncalibrated predictions or extreme probabilities, making the process of taking different decisions based on their output relatively difficult. In this paper we propose to build several inductive Venn--ABERS predictors (IVAP), which are guaranteed to be well calibrated under minimal assumptions, based on a selection of pre-trained transformers. We test their performance over a set of diverse NLU tasks and show that they are capable of producing well-calibrated probabilistic predictions that are uniformly spread over the [0,1] interval -- all while retaining the original model's predictive accuracy.Comment: Accepted at the 11th Symposium on Conformal and Probabilistic Prediction with Applications - COPA 202