The literature on blockchain-based databases is divided into permissioned blockchains and permissionless account-based blockchains. However, the former is not fully decentralized, and the latter suffers from challenges in scalability and practicality. We propose SpendableStore, a hybrid on/off-chain database that operates on top of permissionless UTXO-based blockchains as a novel approach to the problem of data decentralization. Our design integrates atomic data units into individual UTXOs to create a new blockchain concept called Spendable Data Objects that perform traditional CRUD operations. The integrity, immutability, and ownership of these Spendable Data Objects are safeguarded directly by the blockchain peer nodes, thus constraining the power of database administrators to achieve true data decentralization. We further support database transactions and propose an isolation mechanism called Future Now Snapshot Isolation to reason about transactional correctness in SpendableStore. We performed experiments on a major blockchain's Mainnet and observed up to 16x better throughput compared to a state-of-the-art blockchain-based database.

Composed Image Retrieval (CIR) aims to search an image of interest using a combination of a reference image and modification text as the query. Despite recent advancements, this task remains challenging due to limited training data and laborious triplet annotation processes. To address this issue, this paper proposes to synthesize the training triplets to augment the training resource for the CIR problem. Specifically, we commence by training a modification text generator exploiting large-scale multimodal models and scale up the CIR learning throughout both the pretraining and fine-tuning stages. During pretraining, we leverage the trained generator to directly create Modification Text-oriented Synthetic Triplets (MTST) conditioned on pairs of images. For fine-tuning, we first synthesize reverse modification text to connect the target image back to the reference image. Subsequently, we devise a two-hop alignment strategy to incrementally close the semantic gap between the multimodal pair and the target image. We initially learn an implicit prototype utilizing both the original triplet and its reversed version in a cycle manner, followed by combining the implicit prototype feature with the modification text to facilitate accurate alignment with the target image. Extensive experiments validate the efficacy of the generated triplets and confirm that our proposed methodology attains competitive recall on both the CIRR and FashionIQ benchmarks. Codes and datasets will be made publicly accessible.

Blockchain has recently amassed a lot of interest from researchers and practitioners. This is due to its ability to manage data in a decentralized, transparent and accountable manner. However, blockchain applications are limited in terms of compute and cost effectiveness. These limits led to smart contracts—programs that are processed by the blockchain network—being relatively simple, not taking advantage of complex computation methods. In this paper, we shed light on the design space of using machine learning in blockchain applications (we call this ML on Chain for short). Although a lot of work discusses the intersection of blockchain and ML, there is little clarity in mapping, understanding, and evaluating the various approaches in this space. This paper contributes to this new area by the following: (1) we introduce a taxonomy of ML on Chain. This taxonomy considers existing and future potential methods in this area and groups them based on their design characteristics. We consider in the taxonomy five off-chain approaches and a baseline on-chain approach. (2) we perform an extensive experimental evaluation of ML on Chain methods. We compare the different 5 groups of solutions across different settings and three ML model types: logistic regression, k-nearest neighbors and neural networks. (3) Using the taxonomy and experimental study, we provide insights about the current state and challenges of the ML on Chain space; we use this newfound understanding to discuss potential future approaches and provide suggestions to address ML on Chain challenges.

In this paper, we introduce a large Multi-Attribute and Language Search dataset for text-based person retrieval, called MALS, and explore the feasibility of performing pre-training on both attribute recognition and image-text matching tasks in one stone. In particular, MALS contains 1,510,330 image-text pairs, which is about 37.5 × larger than prevailing CUHK-PEDES, and all images are annotated with 27 attributes. Considering the privacy concerns and annotation costs, we leverage the off-the-shelf diffusion models to generate the dataset. To verify the feasibility of learning from the generated data, we develop a new joint Attribute Prompt Learning and Text Matching Learning (APTM) framework, considering the shared knowledge between attribute and text. As the name implies, APTM contains an attribute prompt learning stream and a text matching learning stream. (1) The attribute prompt learning leverages the attribute prompts for image-attribute alignment, which enhances the text matching learning. (2) The text matching learning facilitates the representation learning on fine-grained details, and in turn, boosts the attribute prompt learning. Extensive experiments validate the effectiveness of the pre-training on MALS, achieving state-of-the-art retrieval performance via APTM on three challenging real-world benchmarks. In particular, APTM achieves a consistent improvement of +6.96 %, +7.68%, and +16.95% Recall@1 accuracy on CUHK-PEDES, ICFG-PEDES, and RSTPReid datasets by a clear margin, respectively. The dataset, model, and code are available at https://github.com/Shuyu-XJTU/APTM.

The recently developed memristor technology allows for extremely fast implementation of a number of important matrix operations and algorithms. Moreover, the existence of fast matrix-vector operations offers the opportunity to design new matrix algorithms that exploit these operations. Here, we focus on the spectral decomposition of matrices, a task that plays an important role in a wide variety of applications from different engineering and scientific fields, including network science, control theory, advanced dynamics, and quantum mechanics. While there are a number of algorithms designed to find eigenvalues and eigenvectors of a matrix, these methods often suffer from poor running time performance. In this work, we present an algorithm for finding eigenvalues and eigenvectors that is designed to be used on memristor crossbar arrays. Although this algorithm can be implemented in a non-memristive system, its fast running time relies on the availability of extremely fast matrix-vector multiplication, as is offered by a memristor crossbar array. In this paper, we (1) show the running time improvements of existing eigendecomposition algorithms when matrix-vector multiplications are performed on a memristor crossbar array, and (2) presentEigSweep, a novel, fully-parallel, fast and flexible eigendecomposition algorithm that gives an improvement in running time over traditional eigendecomposition algorithms when all are accelerated by a memristor crossbar. We discuss algorithmic aspects as well as hardware-related aspects of the implementation ofEigSweep, and perform an extensive experimental analysis on real-world and synthetic matrices.

Polygon mesh is among the most common data structures used for representing objects in computer graphics. Unfortunately, a polygon mesh does not capture high-level structures, unlike a hierarchical model. In general, high-level abstractions are useful for managing data in applications. In this paper, we present a method for decomposing an object represented in polygon meshes into components by means of critical points. The method consists of steps to define the root vertex of the object, define a function on the polygon meshes, compute the geodesic tree and critical points, decide the decomposition order, and extract components using backwards flooding. We have implemented the method. The preliminary results show that it works effectively and efficiently. The decomposition results can be useful for applications such as 3D model retrieval and morphing.