feature cluster
Review for NeurIPS paper: Compositional Explanations of Neurons
Summary and Contributions: This paper presents a quite thoughtful and informative attempt to understand what information is encoded in individual neurons and sets of neurons (by which the authors mean units in neural networks, not real brain neurons. This is a somewhat unfortunate use of the word and it might be helpful in the future to talk on neural network units or some other term instead.) It is by now clear to anyone working with these networks that each individual neuron, esp. at the lower and intermediate levels, encodes not some simple human-understandable feature (like color red, size large, wordclass noun, type Person), but rather a complex combination of what one could call sub-facets, which each by itself often not easily described to a human. Combinations of these sub-facets taken from different neurons acting in tandem JOINTLY encode the facets that are more accessible to humans. But of course the other sub-facets also encoded by the neurons present in a human-accessible feature cluster might encode [parts of] a variety of totally unrelated other features, with the result that simple hotspot analysis and similar highlighting techniques are never fully determinate or clear, but always rather ambiguous and'smeared'.
Tackling Polysemanticity with Neuron Embeddings
We present neuron embeddings, a representation that can be used to tackle polysemanticity by One common method for interpreting the behaviour of a neuron identifying the distinct semantic behaviours in a in a language model is to collect and study the dataset examples neuron's characteristic dataset examples, making which cause the highest neuron activation. Patterns downstream manual or automatic interpretation in a neuron's dataset examples provide an indication of what much easier. We apply our method to GPT2-small, the neuron responds to. However, polysemanticity makes and provide a UI for exploring the results. Neuron these dataset examples much harder to interpret, as there embeddings are computed using a model's internal are often many separate behaviours to understand, some representations and weights, making them of which may be related and others entirely distinct. This domain and architecture agnostic and removing becomes increasingly challenging as you collect examples the risk of introducing external structure which further down the activation spectrum, which is important may not reflect a model's actual computation. We for gaining a complete understanding of a neuron, but often describe how neuron embeddings can be used to reveals a wider range of behaviours (Bolukbasi et al., 2021).
A Novel Ontology-guided Attribute Partitioning Ensemble Learning Model for Early Prediction of Cognitive Deficits using Quantitative Structural MRI in Very Preterm Infants
Li, Zhiyuan, Li, Hailong, Braimah, Adebayo, Dillman, Jonathan R., Parikh, Nehal A., He, Lili
Structural magnetic resonance imaging studies have shown that brain anatomical abnormalities are associated with cognitive deficits in preterm infants. Brain maturation and geometric features can be used with machine learning models for predicting later neurodevelopmental deficits. However, traditional machine learning models would suffer from a large feature-to-instance ratio (i.e., a large number of features but a small number of instances/samples). Ensemble learning is a paradigm that strategically generates and integrates a library of machine learning classifiers and has been successfully used on a wide variety of predictive modeling problems to boost model performance. Attribute (i.e., feature) bagging method is the most commonly used feature partitioning scheme, which randomly and repeatedly draws feature subsets from the entire feature set. Although attribute bagging method can effectively reduce feature dimensionality to handle the large feature-to-instance ratio, it lacks consideration of domain knowledge and latent relationship among features. In this study, we proposed a novel Ontology-guided Attribute Partitioning (OAP) method to better draw feature subsets by considering the domain-specific relationship among features. With the better partitioned feature subsets, we developed an ensemble learning framework, which is referred to as OAP-Ensemble Learning (OAP-EL). We applied the OAP-EL to predict cognitive deficits at 2 years of age using quantitative brain maturation and geometric features obtained at term equivalent age in very preterm infants. We demonstrated that the proposed OAP-EL approach significantly outperformed the peer ensemble learning and traditional machine learning approaches.
Why have a Unified Predictive Uncertainty? Disentangling it using Deep Split Ensembles
Sarawgi, Utkarsh, Zulfikar, Wazeer, Khincha, Rishab, Maes, Pattie
Understanding and quantifying uncertainty in black box Neural Networks (NNs) is critical when deployed in real-world settings such as healthcare. Recent works using Bayesian and non-Bayesian methods have shown how a unified predictive uncertainty can be modelled for NNs. Decomposing this uncertainty to disentangle the granular sources of heteroscedasticity in data provides rich information about its underlying causes. We propose a conceptually simple non-Bayesian approach, deep split ensemble, to disentangle the predictive uncertainties using a multivariate Gaussian mixture model. The NNs are trained with clusters of input features, for uncertainty estimates per cluster. We evaluate our approach on a series of benchmark regression datasets, while also comparing with unified uncertainty methods. Extensive analyses using dataset shits and empirical rule highlight our inherently well-calibrated models. Our work further demonstrates its applicability in a multi-modal setting using a benchmark Alzheimer's dataset and also shows how deep split ensembles can highlight hidden modality-specific biases. The minimal changes required to NNs and the training procedure, and the high flexibility to group features into clusters makes it readily deployable and useful. The source code is available at https://github.com/wazeerzulfikar/deep-split-ensembles
Novelty-Prepared Few-Shot Classification
Wang, Chao, Liu, Ruo-Ze, Ye, Han-Jia, Yu, Yang
Few-shot classification algorithms can alleviate the data scarceness issue, which is vital in many real-world problems, by adopting models pre-trained from abundant data in other domains. However, the pre-training process was commonly unaware of the future adaptation to other concept classes. We disclose that a classically fully trained feature extractor can leave little embedding space for unseen classes, which keeps the model from well-fitting the new classes. In this work, we propose to use a novelty-prepared loss function, called self-compacting softmax loss (SSL), for few-shot classification. The SSL can prevent the full occupancy of the embedding space. Thus the model is more prepared to learn new classes. In experiments on CUB-200-2011 and mini-ImageNet datasets, we show that SSL leads to significant improvement of the state-of-the-art performance. This work may shed some light on considering the model capacity for few-shot classification tasks.
Multi-view Information-theoretic Co-clustering for Co-occurrence Data
Xu, Peng, Deng, Zhaohong, Choi, Kup-Sze, Cao, Longbing, Wang, Shitong
Multi-view clustering has received much attention recently. Most of the existing multi-view clustering methods only focus on one-sided clustering. As the co-occurring data elements involve the counts of sample-feature co-occurrences, it is more efficient to conduct two-sided clustering along the samples and features simultaneously. To take advantage of two-sided clustering for the co-occurrences in the scene of multi-view clustering, a two-sided multi-view clustering method is proposed, i.e., multi-view information-theoretic co-clustering (MV-ITCC). The proposed method realizes two-sided clustering for co-occurring multi-view data under the formulation of information theory. More specifically, it exploits the agreement and disagreement among views by sharing a common clustering results along the sample dimension and keeping the clustering results of each view specific along the feature dimension. In addition, the mechanism of maximum entropy is also adopted to control the importance of different views, which can give a right balance in leveraging the agreement and disagreement. Extensive experiments are conducted on text and image multi-view datasets. The results clearly demonstrate the superiority of the proposed method.
An interpretable multiple kernel learning approach for the discovery of integrative cancer subtypes
Speicher, Nora K., Pfeifer, Nico
Due to the complexity of cancer, clustering algorithms have been used to disentangle the observed heterogeneity and identify cancer subtypes that can be treated specifically. While kernel based clustering approaches allow the use of more than one input matrix, which is an important factor when considering a multidimensional disease like cancer, the clustering results remain hard to evaluate and, in many cases, it is unclear which piece of information had which impact on the final result. In this paper, we propose an extension of multiple kernel learning clustering that enables the characterization of each identified patient cluster based on the features that had the highest impact on the result. To this end, we combine feature clustering with multiple kernel dimensionality reduction and introduce FIPPA, a score which measures the feature cluster impact on a patient cluster. Results: We applied the approach to different cancer types described by four different data types with the aim of identifying integrative patient subtypes and understanding which features were most important for their identification. Our results show that our method does not only have state-of-the-art performance according to standard measures (e.g., survival analysis), but, based on the high impact features, it also produces meaningful explanations for the molecular bases of the subtypes. This could provide an important step in the validation of potential cancer subtypes and enable the formulation of new hypotheses concerning individual patient groups. Similar analysis are possible for other disease phenotypes.
A Stratified Feature Ranking Method for Supervised Feature Selection
Chen, Renjie (South China University of Technology, Guangzhou) | Chen, Xiaojun (Shenzhen University, Shenzhen) | Yuan, Guowen (Shenzhen University, Shenzhen) | Sun, Wenya (Shenzhen University, Shenzhen) | Wu, Qingyao (South China University of Technology, Guangzhou)
Most feature selection methods usually select the highest rank features which may be highly correlated with each other. In this paper, we propose a Stratified Feature Ranking (SFR) method for supervised feature selection. In the new method, a Subspace Feature Clustering (SFC) is proposed to identify feature clusters, and a stratified feature ranking method is proposed to rank the features such that the high rank features are lowly correlated. Experimental results show the superiority of SFR.
Multi-Relevance Transfer Learning
Transfer learning aims to faciliate learning tasks in a label-scarce target domain by leveraging knowledge from a related source domain with plenty of labeled data. Often times we may have multiple domains with little or no labeled data as targets waiting to be solved. Most existing efforts tackle target domains separately by modeling the `source-target' pairs without exploring the relatedness between them, which would cause loss of crucial information, thus failing to achieve optimal capability of knowledge transfer. In this paper, we propose a novel and effective approach called Multi-Relevance Transfer Learning (MRTL) for this purpose, which can simultaneously transfer different knowledge from the source and exploits the shared common latent factors between target domains. Specifically, we formulate the problem as an optimization task based on a collective nonnegative matrix tri-factorization framework. The proposed approach achieves both source-target transfer and target-target leveraging by sharing multiple decomposed latent subspaces. Further, an alternative minimization learning algorithm is developed with convergence guarantee. Empirical study validates the performance and effectiveness of MRTL compared to the state-of-the-art methods.