Precoding-Based Network Alignment For Three Unicast Sessions

We consider the problem of network coding across three unicast sessions over a directed acyclic graph, where each sender and the receiver is connected to the network via a single edge of unit capacity. We consider a network model in which the middle of the network only performs random linear network coding, and restrict our approaches to precoding-based linear schemes, where the senders use precoding matrices to encode source symbols. We adapt a precoding-based interference alignment technique, originally developed for the wireless interference channel, to construct a precoding-based linear scheme, which we refer to as as a {\em precoding-based network alignment scheme (PBNA)}. A primary difference between this setting and the wireless interference channel is that the network topology can introduce dependencies between elements of the transfer matrix, which we refer to as coupling relations, and can potentially affect the achievable rate of PBNA. We identify all possible such coupling relations, and interpret these coupling relations in terms of network topology and present polynomial-time algorithms to check the presence of these coupling relations. Finally, we show that, depending on the coupling relations present in the network, the optimal symmetric rate achieved by precoding-based linear scheme can take only three possible values, all of which can be achieved by PBNA.Comment: arXiv admin note: text overlap with arXiv:1202.340

SeamlessM4T-Massively Multilingual & Multimodal Machine Translation

What does it take to create the Babel Fish, a tool that can help individuals translate speech between any two languages? While recent breakthroughs in text-based models have pushed machine translation coverage beyond 200 languages, unified speech-to-speech translation models have yet to achieve similar strides. More specifically, conventional speech-to-speech translation systems rely on cascaded systems that perform translation progressively, putting high-performing unified systems out of reach. To address these gaps, we introduce SeamlessM4T, a single model that supports speech-to-speech translation, speech-to-text translation, text-to-speech translation, text-to-text translation, and automatic speech recognition for up to 100 languages. To build this, we used 1 million hours of open speech audio data to learn self-supervised speech representations with w2v-BERT 2.0. Subsequently, we created a multimodal corpus of automatically aligned speech translations. Filtered and combined with human-labeled and pseudo-labeled data, we developed the first multilingual system capable of translating from and into English for both speech and text. On FLEURS, SeamlessM4T sets a new standard for translations into multiple target languages, achieving an improvement of 20% BLEU over the previous SOTA in direct speech-to-text translation. Compared to strong cascaded models, SeamlessM4T improves the quality of into-English translation by 1.3 BLEU points in speech-to-text and by 2.6 ASR-BLEU points in speech-to-speech. Tested for robustness, our system performs better against background noises and speaker variations in speech-to-text tasks compared to the current SOTA model. Critically, we evaluated SeamlessM4T on gender bias and added toxicity to assess translation safety. Finally, all contributions in this work are open-sourced and accessible at https://github.com/facebookresearch/seamless_communicatio

Precoding-Based Techniques for Multiple Unicasts in Wired and Wireless Networks

In this thesis, we study intersession coding for multiple unicasts in wired and wireless network settings. In particular, we apply alignment techniques and investigate the effect of structure of the transfer matrix to their performance. In addition, we also look at the coded caching problem and we propose an efficient delivery scheme that outperforms state-of-the-art.The thesis is divided into three parts. In the first part, we consider the problem of network coding across three unicast sessions over a directed acyclic graph, where each unicast session has a min-cut of 1. We consider a network model in which the middle of the network can only perform random linear network coding. We adapt interference alignment technique, originally developed for the wireless interference channel, to construct a precoding-based linear scheme, which we refer to as precoding-based network alignment (PBNA). The primary difference between this setting and the wireless interference channel is that the network topology can introduce dependencies among the elements of the transfer matrix and can potentially affect the achievable rate of PBNA.We identify all these dependencies and we interpret them in terms of network topology. We also show that, depending on these network topologies, the optimal symmetric rate achieved by any precoding-based linear scheme can take only three possible values, all of which can be achieved by PBNA.In the second part, we consider the interference channel with $K$ transmitters and $K$ receivers all having a single antenna, wherein the $K \times K$ transfer matrix representing this channel has rank $D$ (less than $K$). The degrees of freedom of such channels are not known as the rank-deficient transfer matrix creates algebraic dependencies between the channel coefficients. We present a modified version of the alignment scheme, to handle these dependencies while aligning interference, and derive the sufficient conditions for achieving half rate per user using this scheme. We show the difficulties in proving these sufficient condition for $K=4$ and $K=5$ and we also show that these sufficient conditions are not satisfied for $K \ge 6$.Finally, we study the coded caching problem: a network with several users trying to access a database of files stored at a server through a shared bottleneck link is considered. Each user is equipped with a cache, where files can be prefetched according to a caching policy, which is mainly based on the popularities of the files. Coded caching tries to exploit coding opportunities created by cooperative caching and has been shown to significantly reduce the load on the shared link. Most prior work focused on optimizing the caching policy so as to minimize this expected load. Given the caching policy and the user demands, the problem of minimizing the load over the shared link is essentially an index coding problem. In this part of the thesis, we design a novel delivery scheme, Heterogeneous Coded Delivery (HCD), that builds on a prior scheme for the uniform demand case, but performs better in the non-uniform demand case. We evaluate this delivery scheme for different caching policies

DEEP LEARNING PLUGIN TOOL USING AN HYBRID RNN-LSTM MODEL TO DETECT AESOPIAN PHRASES IN CYBERBULLYING

ABSTRACT Cyberbullying is a major issue on social media that can cause significant harm to children and teenagers' mental and physical health, in some cases leading to self-harm or suicide. Existing cyberbullying detection systems primarily rely on content moderators built and managed by social media platforms. However, they do not consider complex language features such as slang, multilingualism, or aesopian phrases, which are essential in detecting cyberbullying accurately. This research proposes the world's first AI-based plug-in tool that uses a hybrid RNN-LSTM neural network to automatically detect, anticipate, and classify cyberbullying/prospective incidents while also recognizing false positives. The tool considers patterns across natural language, slang terms, and aesopian phrases that are unique to select groups or communities. The proposed tool can work across languages, browsers, devices, and community-specific phrases to protect children worldwide. The study demonstrates that deep learning techniques can be effectively used for cyberbullying detection, and the proposed tool can have the potential to save over a billion kids on the internet and social media. Keywords: Cyberbullying, Deep learning, RNN-LSTM, Natural Language Processing, Aesopian phrase

Degrees of Freedom of Rank-Deficient MIMO Interference Networks

We characterize the degrees of freedom (DoF) of MIMO interference networks with rank-deficient channel matrices. For the 2-user rank deficient MIMO interference channel, we provethe optimality of previously known achievable DoF in the symmetric case and generalize the re-sult to fully asymmetric settings. For the K-user rank deficient interference channel, we improvethe previously known achievable DoF and provide a tight outer bound to establish optimalityin symmetric settings. In particular, we show that for the K-user rank deficient interferencechannel, when all nodes have M antennas, all direct channels have rank D0, all cross chan-nels are of rank D, and the channels are otherwise generic, the optimal DoF value per user ismin(D0, M −min(M,(K−1)D)). For 2-user and 3-user rank deficient channels, achievable schemes2are for both constant and time-varying channels, while for K-user rank deficient channels, we present schemes for time-varying channels and note that the insights would act as stepping stones for constant channels. Notably for interference channels, the rank-deficiency of direct channels does not help and the rank-deficiency of cross-channels does not hurt. The main technical challenge is to account for the spatial dependencies introduced by rank deficiencies in the interference alignment schemes that typically rely on the independence of channel coefficients

Degrees of Freedom of Rank-Deficient MIMO Interference Networks

We characterize the degrees of freedom (DoF) of MIMO interference networks with rank-deficient channel matrices. For the 2-user rank deficient MIMO interference channel, we provethe optimality of previously known achievable DoF in the symmetric case and generalize the re-sult to fully asymmetric settings. For the K-user rank deficient interference channel, we improvethe previously known achievable DoF and provide a tight outer bound to establish optimalityin symmetric settings. In particular, we show that for the K-user rank deficient interferencechannel, when all nodes have M antennas, all direct channels have rank D0, all cross chan-nels are of rank D, and the channels are otherwise generic, the optimal DoF value per user ismin(D0, M −min(M,(K−1)D)). For 2-user and 3-user rank deficient channels, achievable schemes2are for both constant and time-varying channels, while for K-user rank deficient channels, we present schemes for time-varying channels and note that the insights would act as stepping stones for constant channels. Notably for interference channels, the rank-deficiency of direct channels does not help and the rank-deficiency of cross-channels does not hurt. The main technical challenge is to account for the spatial dependencies introduced by rank deficiencies in the interference alignment schemes that typically rely on the independence of channel coefficients

Network coding for three unicast sessions: Interference alignment approaches

We propose interference alignment techniques, originally developed for wireless interference channels, for the problem of network coding across unicast sessions. We describe two general approaches (namely, coding at the edge or in the middle of the network) and one specific example of each approach (namely, symbol extension method and ergodic alignment, respectively). We discuss the conditions for feasibility of alignment and their relation to network structure. We also compare alignment to alternative approaches. For three unicast sessions with mincut one, we show that whenever alignment is possible, alternative approaches can also achieve half the min-cut. However, for more than three sessions and/or for min-cut per session greater than one, we show examples where alignment is necessary

Road kills of the endemic snake Perrotet’s Shieldtail Plectrurus perrotetii, Dumeril, 1851 (Reptilia: Squamata: Uropeltidae) in Nilgiris, Tamil Nadu, India

Twenty seven road killed specimens of Plectrurus perrotetii were recorded in Emerald and its surrounding areas in the Nilgiris. Among the road kills, fourteen of them were females, seven were males and six are juveniles. Among the road kill female specimens of this species, it was observed that seven were gravid with fully developed young. Three to six developing young ones were observed</p