OpenRaiser/Intern-Atlas huggingface dataset:
Towards Robust Graph Contrastive Learning
Venue: arXiv cs.LG 2021
Year: 2021

We study the problem of adversarially robust self-supervised learning on graphs. In the contrastive learning framework, we introduce a new method that increases the adversarial robustness of the learned representations through i) adversarial transformations and ii) transformations that not only remove but also insert edges. We evaluate the learned representations in a preliminary set of experiments, obtaining promising results. We believe this work takes an important step towards incorporating robustness as a viable auxiliary task in graph contrastive learning.
Nonlinear Projection Based Gradient Estimation for Query Efficient Blackbox Attacks
Venue: arXiv cs.LG 2021
Year: 2021

Gradient estimation and vector space projection have been studied as two distinct topics. We aim to bridge the gap between the two by investigating how to efficiently estimate gradient based on a projected low-dimensional space. We first provide lower and upper bounds for gradient estimation under both linear and nonlinear projections, and outline checkable sufficient conditions under which one is better than the other. Moreover, we analyze the query complexity for the projection-based gradient estimation and present a sufficient condition for query-efficient estimators. Built upon our theoretic analysis, we propose a novel query-efficient Nonlinear Gradient Projection-based Boundary Blackbox Attack (NonLinear-BA). We conduct extensive experiments on four image datasets: ImageNet, CelebA, CIFAR-10, and MNIST, and show the superiority of the proposed methods compared with the state-of-the-art baselines. In particular, we show that the projection-based boundary blackbox attacks are able to achieve much smaller magnitude of perturbations with 100% attack success rate based on efficient queries. Both linear and nonlinear projections demonstrate their advantages under different conditions. We also evaluate NonLinear-BA against the commercial online API MEGVII Face++, and demonstrate the high blackbox attack performance both quantitatively and qualitatively. The code is publicly available at https://github.com/AI-secure/NonLinear-BA.
PlaceRAN: Optimal Placement of Virtualized Network Functions in the Next-generation Radio Access Networks
Venue: arXiv cs.NI 2021
Year: 2021

The fifth-generation mobile evolution enables several transformations on Next Generation Radio Access Networks (NG-RAN). The RAN protocol stack is splitting into eight possible disaggregated options combined into three network units, i.e., Central, Distributed, and Radio. Besides that, further advances allow the RAN software to be virtualized on top of general-purpose vendor-neutral hardware, dealing with the concept of virtualized RAN (vRAN). The disaggregated network units initiatives reach full interoperability based on the Open RAN (O-RAN). The combination of NG-RAN and vRAN results in vNG-RAN, enabling the management of disaggregated units and protocols as a set of radio functions. The placement of these functions is challenging since the best decision can be based on multiple constraints, such as the RAN protocol stack split, routing paths of transport networks with restricted bandwidth and latency requirements, different topologies and link capabilities, asymmetric computational resources, etc. This article proposes the first exact model for the placement optimization of radio functions for vNG-RAN planning, named PlaceRAN. The main objective is to minimize the computing resources and maximize the aggregation of radio functions. The PlaceRAN evaluation considered two realistic network topologies. Our results reveal that the PlaceRAN model achieves an optimized high-performance aggregation level, it is flexible for RAN deployment overcoming the network restrictions, and it is up to date with the most advanced vNG-RAN design and development.
Spurious Local Minima Are Common for Deep Neural Networks with Piecewise Linear Activations
Venue: arXiv cs.LG 2021
Year: 2021

In this paper, it is shown theoretically that spurious local minima are common for deep fully-connected networks and convolutional neural networks (CNNs) with piecewise linear activation functions and datasets that cannot be fitted by linear models. A motivating example is given to explain the reason for the existence of spurious local minima: each output neuron of deep fully-connected networks and CNNs with piecewise linear activations produces a continuous piecewise linear (CPWL) output, and different pieces of CPWL output can fit disjoint groups of data samples when minimizing the empirical risk. Fitting data samples with different CPWL functions usually results in different levels of empirical risk, leading to prevalence of spurious local minima. This result is proved in general settings with any continuous loss function. The main proof technique is to represent a CPWL function as a maximization over minimization of linear pieces. Deep ReLU networks are then constructed to produce these linear pieces and implement maximization and minimization operations.
On Register Linearizability and Termination
Venue: arXiv cs.DC 2021
Year: 2021

In a seminal work, Golab et al. showed that a randomized algorithm that works with atomic objects may lose some of its properties if we replace the atomic objects that it uses with linearizable objects. It was not known whether the properties that can be lost include the important property of termination (with probability 1). In this paper, we first show that, for randomized algorithms, termination can indeed be lost. Golab et al. also introduced strong linearizability, and proved that strongly linearizable objects can be used as if they were atomic objects, even for randomized algorithms: they preserve the algorithm's correctness properties, including termination. Unfortunately, there are important cases where strong linearizability is impossible to achieve. In particular, Helmi et al. MWMR registers do not have strongly linearizable implementations from SWMR registers. So we propose a new type of register linearizability, called write strong-linearizability, that is strictly stronger than linearizability but strictly weaker than strong linearizability. We prove that some randomized algorithms that fail to terminate with linearizable registers, work with write strongly-linearizable ones. In other words, there are cases where linearizability is not sufficient but write strong-linearizability is. In contrast to the impossibility result mentioned above, we prove that write strongly-linearizable MWMR registers are implementable from SWMR registers. Achieving write strong-linearizability, however, is harder than achieving just linearizability: we give a simple implementation of MWMR registers from SWMR registers and we prove that this implementation is linearizable but not write strongly-linearizable. Finally, we prove that any linearizable implementation of SWMR registers is necessarily write strongly-linearizable; this holds for shared-memory, message-passing, and hybrid systems.
Domain Adapting Ability of Self-Supervised Learning for Face Recognition
Venue: arXiv cs.CV 2021
Year: 2021

Although deep convolutional networks have achieved great performance in face recognition tasks, the challenge of domain discrepancy still exists in real world applications. Lack of domain coverage of training data (source domain) makes the learned models degenerate in a testing scenario (target domain). In face recognition tasks, classes in two domains are usually different, so classical domain adaptation approaches, assuming there are shared classes in domains, may not be reasonable solutions for this problem. In this paper, self-supervised learning is adopted to learn a better embedding space where the subjects in target domain are more distinguishable. The learning goal is maximizing the similarity between the embeddings of each image and its mirror in both domains. The experiments show its competitive results compared with prior works. To know the reason why it can achieve such performance, we further discuss how this approach affects the learning of embeddings.
Class Knowledge Overlay to Visual Feature Learning for Zero-Shot Image Classification
Venue: arXiv cs.CV 2021
Year: 2021

New categories can be discovered by transforming semantic features into synthesized visual features without corresponding training samples in zero-shot image classification. Although significant progress has been made in generating high-quality synthesized visual features using generative adversarial networks, guaranteeing semantic consistency between the semantic features and visual features remains very challenging. In this paper, we propose a novel zero-shot learning approach, GAN-CST, based on class knowledge to visual feature learning to tackle the problem. The approach consists of three parts, class knowledge overlay, semi-supervised learning and triplet loss. It applies class knowledge overlay (CKO) to obtain knowledge not only from the corresponding class but also from other classes that have the knowledge overlay. It ensures that the knowledge-to-visual learning process has adequate information to generate synthesized visual features. The approach also applies a semi-supervised learning process to re-train knowledge-to-visual model. It contributes to reinforcing synthesized visual features generation as well as new category prediction. We tabulate results on a number of benchmark datasets demonstrating that the proposed model delivers superior performance over state-of-the-art approaches.
An organized review of key factors for fake news detection
Venue: arXiv cs.SI 2021
Year: 2021

Fake news in social media has quickly become one of the most discussed topics in today's society. With false information proliferating and causing a significant impact in the political, economical, and social domains, research efforts to analyze and automatically identify this type of content have being conducted in the past few years. In this paper, we attempt to summarize the principal findings on the topic of fake news in social media, highlighting the main research path taken and giving a particular focus on the detection of fake news and bot accounts.
Open-Source Verification with Chisel and Scala
Venue: arXiv cs.PL 2021
Year: 2021

Performance increase with general-purpose processors has come to a halt. We can no longer depend on Moore's Law to increase computing performance. The only way to achieve higher performance or lower energy consumption is by building domain-specific hardware accelerators. To efficiently design and verify those domain-specific accelerators, we need agile hardware development. One of the main obstacles when proposing such a modern method is the lack of modern tools to attack it. To be able to verify a design in such a time-constrained development method, one needs to have efficient tools both for design and verification. This paper thus proposes ChiselVerify, an open-source tool for verifying circuits described in any Hardware Description Language. It builds on top of the Chisel hardware construction language and uses Scala to drive the verification using a testing strategy inspired by the Universal Verification Methodology (UVM) and adapted for designs described in Chisel. ChiselVerify is created based on three key ideas. First, our solution highly increases the productivity of the verification engineer, by allowing hardware testing to be done in a modern high-level programming environment. Second, the framework functions with any hardware description language thanks to the flexibility of Chisel blackboxes. Finally, the solution is well integrated into the existing Chisel universe, making it an extension of currently existing testing libraries. We implement ChiselVerify in a way inspired by the functionalities found in SystemVerilog. This allows one to use functional coverage, constrained-random verification, bus functional models, transaction-level modeling and much more during the verification process of a design in a contemporary high-level programming ecosystem.
Leveraged Trading on Blockchain Technology
Venue: arXiv cs.CR 2021
Year: 2021

We document an ongoing research process towards the implementation and integration of a digital artefact, executing the lifecycle of a leveraged trade with permissionless blockchain technology. By employing core functions of the 'Dai Stablecoin system' deployed on the Ethereum blockchain, we produce the equivalent exposure of a leveraged position while deterministically automating the monitoring and liquidation processes. We demonstrate the implementation and early integration of the artefact into a hardened exchange environment through a microservice utilizing standardized API calls. The early results presented in this paper were produced in collaboration with a team of stakeholders at a hosting organization, a multi-national online brokerage and cryptocurrency exchange. We utilize the design science research methodology (DSR) guiding the design, development, and evaluation of the artefact. Our findings indicate that, while it is feasible to implement the lifecycle of a leveraged trade on the blockchain, the integration of the artefact into a traditional exchange environment involves multiple compromises and drawback. Generalizing the tentative findings presented in this paper, we introduce three propositions on the implementation, integration, and implications of executing key business processes with permissionless blockchain technologies. By conducting computational design science research, we contribute to the information systems discourse on the applied utility of permissionless blockchain technologies in finance and beyond.
Eliciting and Analysing Users' Envisioned Dialogues with Perfect Voice Assistants
Venue: arXiv cs.HC 2021
Year: 2021

We present a dialogue elicitation study to assess how users envision conversations with a perfect voice assistant (VA). In an online survey, N=205 participants were prompted with everyday scenarios, and wrote the lines of both user and VA in dialogues that they imagined as perfect. We analysed the dialogues with text analytics and qualitative analysis, including number of words and turns, social aspects of conversation, implied VA capabilities, and the influence of user personality. The majority envisioned dialogues with a VA that is interactive and not purely functional; it is smart, proactive, and has knowledge about the user. Attitudes diverged regarding the assistant's role as well as it expressing humour and opinions. An exploratory analysis suggested a relationship with personality for these aspects, but correlations were low overall. We discuss implications for research and design of future VAs, underlining the vision of enabling conversational UIs, rather than single command "Q&As".
AwkwardForth: accelerating Uproot with an internal DSL
Venue: arXiv cs.PL 2021
Year: 2021

File formats for generic data structures, such as ROOT, Avro, and Parquet, pose a problem for deserialization: it must be fast, but its code depends on the type of the data structure, not known at compile-time. Just-in-time compilation can satisfy both constraints, but we propose a more portable solution: specialized virtual machines. AwkwardForth is a Forth-driven virtual machine for deserializing data into Awkward Arrays. As a language, it is not intended for humans to write, but it loosens the coupling between Uproot and Awkward Array. AwkwardForth programs for deserializing record-oriented formats (ROOT and Avro) are about as fast as C++ ROOT and 10-80$\times$ faster than fastavro. Columnar formats (simple TTrees, RNTuple, and Parquet) only require specialization to interpret metadata and are therefore faster with precompiled code.
Improving ENIGMA-Style Clause Selection While Learning From History
Venue: arXiv cs.AI 2021
Year: 2021

We re-examine the topic of machine-learned clause selection guidance in saturation-based theorem provers. The central idea, recently popularized by the ENIGMA system, is to learn a classifier for recognizing clauses that appeared in previously discovered proofs. In subsequent runs, clauses classified positively are prioritized for selection. We propose several improvements to this approach and experimentally confirm their viability. For the demonstration, we use a recursive neural network to classify clauses based on their derivation history and the presence or absence of automatically supplied theory axioms therein. The automatic theorem prover Vampire guided by the network achieves a 41% improvement on a relevant subset of SMT-LIB in a real time evaluation.
NDVR: NDN Distance Vector Routing
Venue: arXiv cs.NI 2021
Year: 2021

Ad hoc mobile scenarios desire a lightweight routing protocol to propagate rapidly changing data reachability information in a highly dynamic environment. We are developing a distance-vector routing protocol that enables each node to selectively propagate a data reachability vector containing the named-data prefixes current reachable to their neighbors. In this report, we describe the implementation of NDVR (NDN Distance Vector Routing), discuss the rationale for the protocol design choices, and demonstrate a use case for the protocol to illustrate how the routing protocol can help NDN applications, especially in mobile ad-hoc scenarios.
PASSAT: Single Password Authenticated Secret-Shared Intrusion-Tolerant Storage with Server Transparency
Venue: arXiv cs.CR 2021
Year: 2021

In this paper, we introduce PASSAT, a practical system to boost the security assurance delivered by the current cloud architecture without requiring any changes or cooperation from the cloud service providers. PASSAT is an application transparent to the cloud servers that allows users to securely and efficiently store and access their files stored on public cloud storage based on a single master password. Using a fast and light-weight XOR secret sharing scheme, PASSAT secret-shares users' files and distributes them among n publicly available cloud platforms. To access the files, PASSAT communicates with any k out of n cloud platforms to receive the shares and runs a secret-sharing reconstruction algorithm to recover the files. An attacker (insider or outsider) who compromises or colludes with less than k platforms cannot learn the user's files or modify the files stealthily. To authenticate the user to multiple cloud platforms, PASSAT crucially stores the authentication credentials, specific to each platform on a password manager, protected under the user's master password. Upon requesting access to files, the user enters the password to unlock the vault and fetches the authentication tokens using which PASSAT can interact with cloud storage. Our instantiation of PASSAT based on (2, 3)-XOR secret sharing of Kurihara et al., implemented with three popular storage providers, namely, Google Drive, Box, and Dropbox, confirms that our approach can efficiently enhance the confidentiality, integrity, and availability of the stored files with no changes on the servers.
GraphSense: A General-Purpose Cryptoasset Analytics Platform
Venue: arXiv cs.CR 2021
Year: 2021

There is currently an increasing demand for cryptoasset analysis tools among cryptoasset service providers, the financial industry in general, as well as across academic fields. At the moment, one can choose between commercial services or low-level open-source tools providing programmatic access. In this paper, we present the design and implementation of another option: the GraphSense Cryptoasset Analytics Platform, which can be used for interactive investigations of monetary flows and, more importantly, for executing advanced analytics tasks using a standard data science tool stack. By providing a growing set of open-source components, GraphSense could ultimately become an instrument for scientific investigations in academia and a possible response to emerging compliance and regulation challenges for businesses and organizations dealing with cryptoassets.
An Architecture for Memory Centric Active Storage (MCAS)
Venue: arXiv cs.AR 2021
Year: 2021

The advent of CPU-attached persistent memory technology, such as Intel's Optane Persistent Memory Modules (PMM), has brought with it new opportunities for storage. In 2018, IBM Research Almaden began investigating and developing a new enterprise-grade storage solution directly aimed at this emerging technology. MCAS (Memory Centric Active Storage) defines an evolved network-attached key-value store that offers both near-data compute and the ability to layer enterprise-grade data management services on shared persistent memory. As a converged memory-storage tier, MCAS moves towards eliminating the traditional separation of compute and storage, and thereby unifying the data space. This paper provides an in-depth review of the MCAS architecture and implementation, as well as general performance results.
SocNavBench: A Grounded Simulation Testing Framework for Evaluating Social Navigation
Venue: arXiv cs.RO 2021
Year: 2021

The human-robot interaction (HRI) community has developed many methods for robots to navigate safely and socially alongside humans. However, experimental procedures to evaluate these works are usually constructed on a per-method basis. Such disparate evaluations make it difficult to compare the performance of such methods across the literature. To bridge this gap, we introduce SocNavBench, a simulation framework for evaluating social navigation algorithms. SocNavBench comprises a simulator with photo-realistic capabilities and curated social navigation scenarios grounded in real-world pedestrian data. We also provide an implementation of a suite of metrics to quantify the performance of navigation algorithms on these scenarios. Altogether, SocNavBench provides a test framework for evaluating disparate social navigation methods in a consistent and interpretable manner. To illustrate its use, we demonstrate testing three existing social navigation methods and a baseline method on SocNavBench, showing how the suite of metrics helps infer their performance trade-offs. Our code is open-source, allowing the addition of new scenarios and metrics by the community to help evolve SocNavBench to reflect advancements in our understanding of social navigation.
Partitioned Graph Convolution Using Adversarial and Regression Networks for Road Travel Speed Prediction
Venue: arXiv cs.LG 2021
Year: 2021

Access to quality travel time information for roads in a road network has become increasingly important with the rising demand for real-time travel time estimation for paths within road networks. In the context of the Danish road network (DRN) dataset used in this paper, the data coverage is sparse and skewed towards arterial roads, with a coverage of 23.88% across 850,980 road segments, which makes travel time estimation difficult. Existing solutions for graph-based data processing often neglect the size of the graph, which is an apparent problem for road networks with a large amount of connected road segments. To this end, we propose a framework for predicting road segment travel speed histograms for dataless edges, based on a latent representation generated by an adversarially regularized convolutional network. We apply a partitioning algorithm to divide the graph into dense subgraphs, and then train a model for each subgraph to predict speed histograms for the nodes. The framework achieves an accuracy of 71.5% intersection and 78.5% correlation on predicting travel speed histograms using the DRN dataset. Furthermore, experiments show that partitioning the dataset into clusters increases the performance of the framework. Specifically, partitioning the road network dataset into 100 clusters, with approximately 500 road segments in each cluster, achieves a better performance than when using 10 and 20 clusters.