Oceania
PUSH: a primal heuristic based on Feasibility PUmp and SHifting
Grani, Giorgio, Coppola, Corrado, Agasucci, Valerio
Since MIP linear problems include both continuous and integer variables, they are proved to belong to the NP-hard class (see [38] for a more detailed analysis), meaning that they are not solvable in polynomial time. The complete exploration of the integer feasible set, whose cardinality grows exponentially with the number of variables, is yet possible to achieve the optimal solution, but for most of the practically significant instances, it would require unacceptable computational effort. In fact, the only way to solve to optimality any mixed-integer problem is to apply some of the well-known Branch and Bound techniques. However, despite combinatorial optimization community provided a great deal of these algorithms, for which the reader should refer to [31, 34, 16], MIP problems complexity is inherent with their belonging to NP-hard class. Therefore, when tackling MIP problems, one either seeks particular structures allowing to bring down the complexity, such as the availability, for a given class of problems, of the optimal formulation or exploits cutting plane generation to dramatically reduce the feasible region dimension. However, we often encounter MIP problems without having any prior knowledge of possible structures and, thus, pursuing the globally optimal solution could be in practice impossible or inefficient, since for our purpose a sub-optimal approximation is considered to be good enough. This makes heuristics one of the most widespread and feasible ways to achieve sub-optimal solutions of MIP problems within an affordable computational time. For the purpose of highlighting the perspective of our research, we can define two classes of MIP heuristics: improvement heuristics and start heuristics.
Efficient Compilation and Mapping of Fixed Function Combinational Logic onto Digital Signal Processors Targeting Neural Network Inference and Utilizing High-level Synthesis
Shahsavani, Soheil Nazar, Fayyazi, Arash, Nazemi, Mahdi, Pedram, Massoud
They support simple Boolean operations as well as complicated arithmetic operations such as multiplication in a single instruction, multiple data (SIMD) scheme. DSPs have evolved to support a wide range of applications requiring significant amounts of Boolean operations that may not even necessarily fit on the available lookup tables (LUTs) on an FPGA. In addition to the vast computation capabilities, DSP blocks support dynamic runtime programmability, which allows a single DSP block to be used as a different computational block in each clock cycle. Vendor synthesis tools provide capabilities to utilize the available resources on FPGAs; however, existing tool flows such as high-level synthesis tools fail to fully exploit the existing capabilities, especially the dynamic programmability of DSPs. Bajaj et al. [10-14] explore how DSP blocks can be deployed to produce high-throughput computational kernels and how their dynamic programmability can be exploited to create efficient implementations of arithmetic expressions. However, their solution suffers from inefficient mapping when it comes to implementing combinational Boolean functions using DSP blocks.
A Bayesian Approach to Learning Bandit Structure in Markov Decision Processes
Zhang, Kelly W., Gottesman, Omer, Doshi-Velez, Finale
In the reinforcement learning literature, there are many algorithms developed for either Contextual Bandit (CB) or Markov Decision Processes (MDP) environments. However, when deploying reinforcement learning algorithms in the real world, even with domain expertise, it is often difficult to know whether it is appropriate to treat a sequential decision making problem as a CB or an MDP. In other words, do actions affect future states, or only the immediate rewards? Making the wrong assumption regarding the nature of the environment can lead to inefficient learning, or even prevent the algorithm from ever learning an optimal policy, even with infinite data. In this work we develop an online algorithm that uses a Bayesian hypothesis testing approach to learn the nature of the environment. Our algorithm allows practitioners to incorporate prior knowledge about whether the environment is that of a CB or an MDP, and effectively interpolate between classical CB and MDP-based algorithms to mitigate against the effects of misspecifying the environment. We perform simulations and demonstrate that in CB settings our algorithm achieves lower regret than MDP-based algorithms, while in non-bandit MDP settings our algorithm is able to learn the optimal policy, often achieving comparable regret to MDP-based algorithms.
Adding Context to Source Code Representations for Deep Learning
Tian, Fuwei, Treude, Christoph
Deep learning models have been successfully applied to a variety of software engineering tasks, such as code classification, summarisation, and bug and vulnerability detection. In order to apply deep learning to these tasks, source code needs to be represented in a format that is suitable for input into the deep learning model. Most approaches to representing source code, such as tokens, abstract syntax trees (ASTs), data flow graphs (DFGs), and control flow graphs (CFGs) only focus on the code itself and do not take into account additional context that could be useful for deep learning models. In this paper, we argue that it is beneficial for deep learning models to have access to additional contextual information about the code being analysed. We present preliminary evidence that encoding context from the call hierarchy along with information from the code itself can improve the performance of a state-of-the-art deep learning model for two software engineering tasks. We outline our research agenda for adding further contextual information to source code representations for deep learning.
Midway Dental Supply Designates Pearl as Preferred AI Solutions Provider
Pearl, the leader in dental AI solutions, and Midway Dental, one of the leading dental technology and supply distributors in the United States, announced that Pearl is now Midway's preferred artificial intelligence (AI) solutions provider. Pearl's Practice Intelligence AI solution is already available as part of Midway's cutting-edge product sales and distribution inventory, and the collaboration will now also include Second Opinion, the first and only FDA-cleared chairside AI software to help dentists detect numerous conditions in x-rays of dental patients 12 and older. "Our partnership with Midway ensures that forward-thinking dental practices across the U.S. have access to the most advanced AI to streamline their practice management and real-time chairside radiologic evaluations" With over 15,000 dental customers, Michigan-based Midway Dental is the fastest growing full-service dental supply company in the United States, aiming to transform the dental supply industry into something new and progressive. By selecting Pearl as its preferred AI service provider, Midway has reaffirmed its commitment to empowering dental care providers with the most advanced dental technologies for better patient communication, trust, and treatment outcomes. "We selected Pearl as our preferred AI service provider because it is the only dental AI company that can actually deliver on AI's promise for our customers," said Steve Kizy, president of Midway.
SHAP for additively modeled features in a boosted trees model
An important technique to explore a black-box machine learning (ML) model is called SHAP (SHapley Additive exPlanation). SHAP values decompose predictions into contributions of the features in a fair way. We will show that for a boosted trees model with some or all features being additively modeled, the SHAP dependence plot of such a feature corresponds to its partial dependence plot up to a vertical shift. We illustrate the result with XGBoost.
Generating Diverse Realistic Laughter for Interactive Art
Afsar, M. Mehdi, Park, Eric, Paquette, Étienne, Gidel, Gauthier, Mathewson, Kory W., Muller, Eilif
We propose an interactive art project to make those rendered invisible by the COVID-19 crisis and its concomitant solitude reappear through the welcome melody of laughter, and connections created and explored through advanced laughter synthesis approaches. However, the unconditional generation of the diversity of human emotional responses in high-quality auditory synthesis remains an open problem, with important implications for the application of these approaches in artistic settings. We developed LaughGANter, an approach to reproduce the diversity of human laughter using generative adversarial networks (GANs). When trained on a dataset of diverse laughter samples, LaughGANter generates diverse, high quality laughter samples, and learns a latent space suitable for emotional analysis and novel artistic applications such as latent mixing/interpolation and emotional transfer.
A Learned Index for Exact Similarity Search in Metric Spaces
Tian, Yao, Yan, Tingyun, Zhao, Xi, Huang, Kai, Zhou, Xiaofang
Indexing is an effective way to support efficient query processing in large databases. Recently the concept of learned index, which replaces or complements traditional index structures with machine learning models, has been actively explored to reduce storage and search costs. However, accurate and efficient similarity query processing in high-dimensional metric spaces remains to be an open challenge. In this paper, we propose a novel indexing approach called LIMS that uses data clustering, pivot-based data transformation techniques and learned indexes to support efficient similarity query processing in metric spaces. In LIMS, the underlying data is partitioned into clusters such that each cluster follows a relatively uniform data distribution. Data redistribution is achieved by utilizing a small number of pivots for each cluster. Similar data are mapped into compact regions and the mapped values are totally ordinal. Machine learning models are developed to approximate the position of each data record on disk. Efficient algorithms are designed for processing range queries and nearest neighbor queries based on LIMS, and for index maintenance with dynamic updates. Extensive experiments on real-world and synthetic datasets demonstrate the superiority of LIMS compared with traditional indexes and state-of-the-art learned indexes.
Weakly Supervised Deep Instance Nuclei Detection using Points Annotation in 3D Cardiovascular Immunofluorescent Images
Moradinasab, Nazanin, Sharma, Yash, Shankman, Laura S., Owens, Gary K., Brown, Donald E.
Two major causes of death in the United States and worldwide are stroke and myocardial infarction. The underlying cause of both is thrombi released from ruptured or eroded unstable atherosclerotic plaques that occlude vessels in the heart (myocardial infarction) or the brain (stroke). Clinical studies show that plaque composition plays a more important role than lesion size in plaque rupture or erosion events. To determine the plaque composition, various cell types in 3D cardiovascular immunofluorescent images of plaque lesions are counted. However, counting these cells manually is expensive, time-consuming, and prone to human error. These challenges of manual counting motivate the need for an automated approach to localize and count the cells in images. The purpose of this study is to develop an automatic approach to accurately detect and count cells in 3D immunofluorescent images with minimal annotation effort. In this study, we used a weakly supervised learning approach to train the HoVer-Net segmentation model using point annotations to detect nuclei in fluorescent images. The advantage of using point annotations is that they require less effort as opposed to pixel-wise annotation. To train the HoVer-Net model using point annotations, we adopted a popularly used cluster labeling approach to transform point annotations into accurate binary masks of cell nuclei. Traditionally, these approaches have generated binary masks from point annotations, leaving a region around the object unlabeled (which is typically ignored during model training). However, these areas may contain important information that helps determine the boundary between cells. Therefore, we used the entropy minimization loss function in these areas to encourage the model to output more confident predictions on the unlabeled areas. Our comparison studies indicate that the HoVer-Net model trained using our weakly ...
Text and author-level political inference using heterogeneous knowledge representations
da Silva, Samuel Caetano, Paraboni, Ivandre
The inference of politically-charged information from text data is a popular research topic in Natural Language Processing (NLP) at both text- and author-level. In recent years, studies of this kind have been implemented with the aid of representations from transformers such as BERT. Despite considerable success, however, we may ask whether results may be improved even further by combining transformed-based models with additional knowledge representations. To shed light on this issue, the present work describes a series of experiments to compare alternative model configurations for political inference from text in both English and Portuguese languages. Results suggest that certain text representations - in particular, the combined use of BERT pre-trained language models with a syntactic dependency model - may outperform the alternatives across multiple experimental settings, making a potentially strong case for further research in the use of heterogeneous text representations in these and possibly other NLP tasks.