Representation Learning with Relational Data

图是一种普遍存在的数据结构，广泛应用于计算机科学和相关领域。社会网络、分子图结构、生物蛋白质-蛋白质网络、推荐系统——所有这些领域以及更多的领域都可以很容易地建模为图，这些图可以捕获单个实体（即节点）之间的关系（即边）。然而，图不仅作为结构化知识库有用：许多机器学习应用程序试图使用图结构数据作为输入进行预测或发现新的模式。例如，人们可能希望在生物相互作用图中对蛋白质的作用进行分类，在社交网络中向用户推荐新朋友，或者预测现有药物分子的新治疗应用，其结构可以用图表示。图机器学习的核心问题是找到一种将图结构信息编码到机器学习模型中的方法。例如，在社交网络中的链接预测中，可能需要对节点之间的成对属性进行编码，例如关系强度或共同朋友的数量。或者在对蛋白质在生物相互作用网络中的作用进行分类的情况下，人们可能希望包含有关蛋白质局部图邻域结构的信息。在我的研究计划中，我将探索一种新兴的、但发展迅速的图机器学习方法：基于图表示学习（GRL）的方法。这些方法背后的关键思想是嵌入节点或整个（子）图，作为学习到的低维向量空间中的点，并使用神经网络来推理这些学习到的向量空间中的关系交互。传统方法在应用标准机器学习算法之前提取图形统计数据作为预处理步骤，而GRL方法直接以端到端方式使用图结构数据进行学习。虽然这些方法仍处于萌芽阶段，但它们已经在许多图分析任务中显示出相当大的前景。由于图结构数据的无处不在，GRL具有广泛的潜在应用，从化学合成到社会网络分析。在之前的研究中，我开发了GRL方法来预测药物-疾病相互作用，在网络论坛中模拟复杂的社会互动，并为Pinterest Inc.的生产规模推荐系统提供动力。在未来的几年里，我将继续追求这些核心应用主题，特别是与计算社会科学和计算生物学相关的应用。生物学和社会科学领域的许多科学家现在拥有大量的结构化数据，但缺乏有效理解和使用这些数据的计算工具。我研究的一个重点将是开发基于grl的模型，帮助这些领域专家利用这些数据进行大规模的知识发现。

Graphs are a ubiquitous data structure employed extensively within computer science and related fields. Social networks, molecular graph structures, biological protein-protein networks, recommender systems-all of these domains and many more can be readily modeled as graphs, which capture relations (i.e., edges) between individual entities (i.e., nodes). However, graphs are not only useful as structured knowledge repositories: many machine learning applications seek to make predictions or discover new patterns using graph-structured data as input. For example, one might wish to classify the role of a protein in a biological interaction graph, recommend new friends to a user in a social network, or predict new therapeutic applications of existing drug molecules whose structure can be represented as a graph. The central problem in machine learning with graphs is finding a way to encode information about graph-structure into a machine learning model. For example, in the case of link prediction in a social network, one might want to encode pairwise properties between nodes, such as relationship strength or the number of common friends. Or in the case of classifying a protein's role in a biological interaction network, one might want to include information about the structure of the protein's local graph neighborhood. In my research program, I will explore a nascent, but quickly developing class of approaches to machine learning with graphs: approaches based on graph representation learning (GRL). The key idea behind these approaches is to embed nodes, or entire (sub)graphs, as points in a learned low-dimensional vector space and to use neural networks to reason about relational interactions in these learned vector spaces. Whereas traditional approaches would extract graph statistics as a pre-processing step before applying standard machine learning algorithms, GRL approaches directly learn using graph-structured data in an end-to-end fashion. While still in their nascency, these methods have shown considerable promise across numerous graph analysis tasks. Due to the ubiquity of graph-structured data, GRL has wide range of potential applications, ranging from chemical synthesis to social network analysis. In previous research, I have developed GRL methods to predict drug-disease interactions, to model complex social interactions in web forums, and to power a production-scale recommender system at Pinterest Inc. Over the coming years, I will continue to pursue these core application themes, especially applications related to computational social science and computational biology. Many domain scientists in biology and the social sciences now possess massive troves of structured data but lack the computational tools to effectively understand and use it. A key focus of my research will be developing GRL-based models that can aid such domain experts in leveraging this data for large-scale knowledge discovery.