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Sparse $ε$ insensitive zone bounded asymmetric elastic net support vector machines for pattern classification

arXiv.org Machine Learning

Existing support vector machines(SVM) models are sensitive to noise and lack sparsity, which limits their performance. To address these issues, we combine the elastic net loss with a robust loss framework to construct a sparse $\varepsilon$-insensitive bounded asymmetric elastic net loss, and integrate it with SVM to build $\varepsilon$ Insensitive Zone Bounded Asymmetric Elastic Net Loss-based SVM($\varepsilon$-BAEN-SVM). $\varepsilon$-BAEN-SVM is both sparse and robust. Sparsity is proven by showing that samples inside the $\varepsilon$-insensitive band are not support vectors. Robustness is theoretically guaranteed because the influence function is bounded. To solve the non-convex optimization problem, we design a half-quadratic algorithm based on clipping dual coordinate descent. It transforms the problem into a series of weighted subproblems, improving computational efficiency via the $\varepsilon$ parameter. Experiments on simulated and real datasets show that $\varepsilon$-BAEN-SVM outperforms traditional and existing robust SVMs. It balances sparsity and robustness well in noisy environments. Statistical tests confirm its superiority. Under the Gaussian kernel, it achieves better accuracy and noise insensitivity, validating its effectiveness and practical value.


Unlearning or Concealment? A Critical Analysis and Evaluation Metrics for Unlearning in Diffusion Models

arXiv.org Artificial Intelligence

Recent research has seen significant interest in methods for concept removal and targeted forgetting in diffusion models. In this paper, we conduct a comprehensive white-box analysis to expose significant vulnerabilities in existing diffusion model unlearning methods. We show that the objective functions used for unlearning in the existing methods lead to decoupling of the targeted concepts (meant to be forgotten) for the corresponding prompts. This is concealment and not actual unlearning, which was the original goal. The ineffectiveness of current methods stems primarily from their narrow focus on reducing generation probabilities for specific prompt sets, neglecting the diverse modalities of intermediate guidance employed during the inference process. The paper presents a rigorous theoretical and empirical examination of four commonly used techniques for unlearning in diffusion models. We introduce two new evaluation metrics: Concept Retrieval Score (CRS) and Concept Confidence Score (CCS). These metrics are based on a successful adversarial attack setup that can recover forgotten concepts from unlearned diffusion models. The CRS measures the similarity between the latent representations of the unlearned and fully trained models after unlearning. It reports the extent of retrieval of the forgotten concepts with increasing amount of guidance. The CCS quantifies the confidence of the model in assigning the target concept to the manipulated data. It reports the probability of the unlearned model's generations to be aligned with the original domain knowledge with increasing amount of guidance. Evaluating existing unlearning methods with our proposed stringent metrics for diffusion models reveals significant shortcomings in their ability to truly unlearn concepts. Source Code: https://respailab.github.io/unlearning-or-concealment


A Knowledge Plug-and-Play Test Bed for Open-domain Dialogue Generation

arXiv.org Artificial Intelligence

Knowledge-based, open-domain dialogue generation aims to build chit-chat systems that talk to humans using mined support knowledge. Many types and sources of knowledge have previously been shown to be useful as support knowledge. Even in the era of large language models, response generation grounded in knowledge retrieved from additional up-to-date sources remains a practically important approach. While prior work using single-source knowledge has shown a clear positive correlation between the performances of knowledge selection and response generation, there are no existing multi-source datasets for evaluating support knowledge retrieval. Further, prior work has assumed that the knowledge sources available at test time are the same as during training. This unrealistic assumption unnecessarily handicaps models, as new knowledge sources can become available after a model is trained. In this paper, we present a high-quality benchmark named multi-source Wizard of Wikipedia (Ms.WoW) for evaluating multi-source dialogue knowledge selection and response generation. Unlike existing datasets, it contains clean support knowledge, grounded at the utterance level and partitioned into multiple knowledge sources. We further propose a new challenge, dialogue knowledge plug-and-play, which aims to test an already trained dialogue model on using new support knowledge from previously unseen sources in a zero-shot fashion.


Generalized Bayesian Posterior Expectation Distillation for Deep Neural Networks

arXiv.org Machine Learning

Monte Carlo methods provide one solution to represent neural network parameter posteriors as ensembles of networks, but this requires In this paper, we present a general framework large amounts of both storage and compute time (Neal, for distilling expectations with respect to the 1996; Welling and Teh, 2011). Bayesian posterior distribution of a deep neural network classifier, extending prior work on To help overcome these problems, Balan et al. (2015) introduced the Bayesian Dark Knowledge framework. The a model training method referred to as Bayesian proposed framework takes as input "teacher" Dark Knowledge (BDK). BDK attempts to compress (or and student model architectures and a general distill) the Bayesian posterior predictive distribution induced posterior expectation of interest. The distillation by the full parameter posterior of a "teacher" network method performs an online compression (represented via a set of Mote Carlo samples) into a of the selected posterior expectation using iteratively significantly more compact "student" network. The major generated Monte Carlo samples. We advantage of BDK is that the computational complexity focus on the posterior predictive distribution of prediction at test time is drastically reduced compared and expected entropy as distillation targets. We to directly computing predictions via Monte Carlo averages investigate several aspects of this framework over the set of teacher network samples (the teacher including the impact of uncertainty and the ensemble).