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New method improves knowledge-graph-based question answering

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Question answering is a popular task in natural-language processing, where models are given questions such as “What city is the Mona Lisa in?” and trained to predict correct answers, such as “Paris”. 

One way to train question-answering models is to use a knowledge graph, which stores facts about the world in a structured format. Historically, knowledge-graph-based question-answering systems required separate semantic-parsing and entity resolution models, which were costly to train and maintain. But since 2020, the field has been moving toward differentiable knowledge graphs, which allow a single end-to-end model to take questions as inputs and directly output answers.

At this year’s Conference on Empirical Methods in Natural Language Processing (EMNLP), we presented two extensions to end-to-end question answering using differentiable knowledge graphs.

In “End-to-end entity resolution and question answering using differentiable knowledge graphs”, we explain how to integrate entity resolution into a knowledge-graph-based question-answering model, so that it will be performed automatically. This is a potentially labor-saving innovation, as some existing approaches require hand annotation of entities.

And in “Expanding end-to-end question answering on differentiable knowledge graphs with intersection”, we explain how to handle queries that involve multiple entities. In experiments involving two different datasets, our approach improved performance on multi-entity queries by 14% and 19%.

Traditional approaches

In a typical knowledge graph, the nodes represent entities, and the edges between nodes represent relationships between entities. For example, a knowledge graph could contain the fact “Mona Lisa | exhibited at | Louvre Museum”, which links the entities “Mona Lisa” and “Louvre Museum” with the relationship “exhibited at”. Similarly, the graph could link the entities “Louvre Museum” and “Paris” with the relationship “located in”. A model can learn to use the facts in the knowledge graph to get to answer questions.

Question answering through traversal of links in a knowledge graph.

Traditional approaches to knowledge-graph-based question answering use a pipeline of models. First, the question goes into a semantic-parsing model, which is trained to predict queries. Queries can be thought of as instructions of what to do in the knowledge graph — for example, “find out where the ‘Mona Lisa’ is exhibited, then look up what city it’s in.” 

Next, the question goes into an entity resolution model, which links parts of the sentence, like “Mona Lisa”, to IDs in the knowledge graph, like Q12418.

The pipelined approach to knowledge-graph-based question answering.

While this pipeline approach works, it does have some flaws. Each model is trained independently, so it has to be evaluated and updated separately, and each model requires annotations for training, which are time-consuming and expensive to collect. 

End-to-end question answering

End-to-end question answering is a way to rectify these flaws. During training, an end-to-end question answering model is given the question and the answer but no instructions about what to do in the knowledge graph. Instead, the model learns the instructions based on the correct answer. 

In 2020, Cohen et al. proposed a way to perform end-to-end question answering using differentiable knowledge graphs, which represent knowledge graphs as tensors and queries as differentiable mathematical operations. This allows for fully differentiable training, so that the answer alone provides a training signal to update all parts of the model.

End-to-end question answering with a differentiable knowledge graph.

“End-to-end entity resolution and question answering using differentiable knowledge graphs”

In our first paper, we extend end-to-end models to include the training of an entity resolution component. Previous work left the task of entity resolution (linking “Mona Lisa” to Q12418) out of the scope of the model, relying instead on a separate entity resolution model or hand annotation of entities. 

We propose a way to train entity resolution as part of the question-answering model. To do this, we start with a baseline model similar to the implementation by Cohen et al., which has an encoder-decoder structure and an attention mechanism that takes in a question and returns predicted answers with probabilities.

We add entity resolution to this baseline model by first introducing a span detection component. This identifies all the possible parts of the sentence (spans) that could refer to an entity. For example, in the question “Who wrote films starring Tom Hanks?”, there are multiple spans, such as “films” or “Tom”, and we want the model to learn to give a higher score to the correct span, “Tom Hanks”. 

An end-to-end model that jointly learns knowledge-graph-based question answering and entity resolution.

Then for each of the identified spans, our model ranks all the possible entities in the knowledge graph that the span could refer to. For example, “Tom Hanks” is also the name of a seismologist and a theologian, but we want the model to learn to give the actor a higher score.

Span detection and entity resolution happen jointly in a new entity resolution component, which returns possible entities with scores. Finding the entities in the knowledge graph and following the paths from the inference component yields the predicted answers. We believe that this joint modeling is responsible for our method’s increase in efficiency.

In our experiments, we use two English question-answering datasets. We find that although our ER and E2E models perform slightly worse than the baseline, they do come very close, with differences of about 7% and 5% on the two datasets. 

This is an impressive result, since the baseline model uses hand-annotated entities from the datasets, while our model is learning entity resolution jointly with question answering. With these findings, we demonstrate the feasibility of learning to perform entity resolution and multihop inference in a single end-to-end model.

“Expanding end-to-end question answering on differentiable knowledge graphs with intersection”

In our second paper, we extend end-to-end models to handle more complex questions with multiple entities. Take for example the question “Who did Natalie Portman play in Star Wars?”. This question has two entities, Natalie Portman and Star Wars. 

Previous end-to-end models were trained to follow paths originating with one entity in a knowledge graph. However, this is not enough to answer questions with multiple entities. If we started at “Natalie Portman” and found all the roles she played, we would get roles that were not in Star Wars. If we started at Star Wars and found all the characters, we would get characters that Natalie Portman didn’t play. What we need is an intersection of the characters played by Natalie Portman and the characters in Star Wars. 

To handle questions with multiple entities, we expand an end-to-end model with a new operation: intersection. For each entity in the question, the model follows paths from the entity independently and arrives at an intermediate answer. Then the model performs intersection, which we implemented as the element-wise minimum of two vectors, to identify which entities the intermediate answers have in common. Only entities that appear in all intermediate answers are returned in the final answer. 

An end-to-end knowledge-graph-based question-answering model for queries with multiple entities.

In our experiments, we use two English question-answering datasets. Our results show that introducing intersection improves performance over the baseline by 3.7% on one and 8.9% on the other. 

More importantly, we see that improved performance comes from better handling of questions with multiple entities, where the intersection model surpasses the baseline by over 14% on one dataset and by 19% on the other.

In future work, we plan to continue developing end-to-end models by improving entity resolution, so it’s competitive with hand annotation of entities; integrating entity resolution with intersection; and learning to handle more-complex operations, such as maximums/minimums and counts.





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A New Ranking Framework for Better Notification Quality on Instagram

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  • We’re sharing how Meta is applying machine learning (ML) and diversity algorithms to improve notification quality and user experience. 
  • We’ve introduced a diversity-aware notification ranking framework to reduce uniformity and deliver a more varied and engaging mix of notifications.
  • This new framework reduces the volume of notifications and drives higher engagement rates through more diverse outreach.

Notifications are one of the most powerful tools for bringing people back to Instagram and enhancing engagement. Whether it’s a friend liking your photo, another close friend posting a story, or a suggestion for a reel you might enjoy, notifications help surface moments that matter in real time.

Instagram leverages machine learning (ML) models to decide who should get a notification, when to send it, and what content to include. These models are trained to optimize for user positive engagement such as click-through-rate (CTR) – the probability of a user clicking a notification – as well as other metrics like time spent.

However, while engagement-optimized models are effective at driving interactions, there’s a risk that they might overprioritize the product types and authors someone has previously engaged with. This can lead to overexposure to the same creators or the same product types while overlooking other valuable and diverse experiences. 

This means people could miss out on content that would give them a more balanced, satisfying, and enriched experience. Over time, this can make notifications feel spammy and increase the likelihood that people will disable them altogether. 

The real challenge lies in finding the right balance: How can we introduce meaningful diversity into the notification experience without sacrificing the personalization and relevance people on Instagram have come to expect?

To tackle this, we’ve introduced a diversity-aware notification ranking framework that helps deliver more diverse, better curated, and less repetitive notifications. This framework has significantly reduced daily notification volume while improving CTR. It also introduces several benefits:

  • The extensibility of incorporating customized soft penalty (demotion) logic for each dimension, enabling more adaptive and sophisticated diversity strategies.
  • The flexibility of tuning demotion strength across dimensions like content, author, and product type via adjustable weights.
  • The integration of balancing personalization and diversity, ensuring notifications remain both relevant and varied.

The Risks of Notifications without Diversity

The issue of overexposure in notifications often shows up in two major ways:

Overexposure to the same author: People might receive notifications that are mostly about the same friend. For example, if someone often interacts with content from a particular friend, the system may continue surfacing notifications from that person alone – ignoring other friends they also engage with. This can feel repetitive and one-dimensional, reducing the overall value of notifications.

Overexposure to the same product surface: People might mostly receive notifications from the same product surface such as Stories, even when Feed or Reels could provide value. For example, someone may be interested in both reel and story notifications but has recently interacted more often with stories. Because the system heavily prioritizes past engagement, it sends only story notifications, overlooking the person’s broader interests. 

Introducing Instagram’s Diversity-Aware Notification Ranking Framework

Instagram’s diversity-aware notification ranking framework is designed to enhance the notification experience by balancing the predicted potential for user engagement with the need for content diversity. This framework introduces a diversity layer on top of the existing engagement ML models, applying multiplicative penalties to the candidate scores generated by these models, as figure1, below, shows.

The diversity layer evaluates each notification candidate’s similarity to recently sent notifications across multiple dimensions such as content, author, notification type, and product surface. It then applies carefully calibrated penalties—expressed as multiplicative demotion factors—to downrank candidates that are too similar or repetitive. The adjusted scores are used to re-rank the candidates, enabling the system to select notifications that maintain high engagement potential while introducing meaningful diversity. In the end, the quality bar selects the top-ranked candidate that passes both the ranking and diversity criteria.

Figure.1: Instagram’s diversity-aware ranking framework where the diversity layer sits on top of the existing modeling layer and penalizes notifications that are too similar to recently sent ones.

Mathematical Formulation 

Within the diversity layer, we apply a multiplicative demotion factor to the base relevance score of each candidate. Given a notification candidate 𝑐, we compute its final score as the product of its base ranking score and a diversity demotion multiplier:

\text{Score}(c) = R(c) \times D(c)

where R(c) represents the candidate’s base relevance score, and D(c) ∈ [0,1] is a penalty factor that reduces the score based on similarity to recently sent notifications. We define a set of semantic dimensions (e.g., author, product type) along which we want to promote diversity. For each dimension i, we compute a similarity signal pi(c) between candidate c and the set of historical notifications H, using a maximal marginal relevance (MMR) approach:

p_i(c) = \mathrm{max}_{h \in H}\mathrm{sim}_i(c, h)

where simi(·,·) is a predefined similarity function for dimension i. In our baseline implementation, pi(c) is binary: it equals 1 if the similarity exceeds a threshold 𝜏i and 0 otherwise. 

The final demotion multiplier is defined as: 

D(c) = \prod_{i=1}^{m} \left( 1 - w_i \cdot p_i(c) \right)

where each w∈ [0,1] controls the strength of demotion for its respective dimension. This formulation ensures that candidates similar to previously delivered notifications along one or more dimensions are proportionally down-weighted, reducing redundancy and promoting content variation. The use of a multiplicative penalty allows for flexible control across multiple dimensions, while still preserving high-relevance candidates.

The Future of Diversity-Aware Ranking

As we continue evolving our notification diversity-aware ranking system, a next step is to introduce more adaptive, dynamic demotion strategies. Instead of relying on static rules, we plan to make demotion strength responsive to notification volume and delivery timing. For example, as a user receives more notifications—especially of similar type or in rapid succession—the system progressively applies stronger penalties to new notification candidates, effectively mitigating overwhelming experiences caused by high notification volume or tightly spaced deliveries.

Longer term, we see an opportunity to bring large language models (LLMs) into the diversity pipeline. LLMs can help us go beyond surface-level rules by understanding semantic similarity between messages and rephrasing content in more varied, user-friendly ways. This would allow us to personalize notification experiences with richer language and improved relevance while maintaining diversity across topics, tone, and timing.





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Simplifying book discovery with ML-powered visual autocomplete suggestions

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Every day, millions of customers search for books in various formats (audiobooks, e-books, and physical books) across Amazon and Audible. Traditional keyword autocomplete suggestions, while helpful, usually require several steps before customers find their desired content. Audible took on the challenge of making book discovery more intuitive and personalized while reducing the number of steps to purchase.

We developed an instant visual autocomplete system that enhances the search experience across Amazon and Audible. As the user begins typing a query, our solution provides visual previews with book covers, enabling direct navigation to relevant landing pages instead of the search result page. It also delivers real-time personalized format recommendations and incorporates multiple searchable entities, such as book pages, author pages, and series pages.

Our system needed to understand user intent from just a few keystrokes and determine the most relevant books to display, all while maintaining low latency for millions of queries. Using historical search data, we match keystrokes to products, transforming partial inputs into meaningful search suggestions. To ensure quality, we implemented confidence-based filtering mechanisms, which are particularly important for distinguishing between general queries like “mystery” and specific title searches. To reflect customers’ most recent interests, the system applies time-decay functions to long historical user interaction data.

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Assessing the absolute utility of query results, rather than just their relative utility, improves learning-to-rank models.

To meet the unique requirements of each use case, we developed two distinct technical approaches. On Audible, we deployed a deep pairwise-learning-to-rank (DeepPLTR) model. The DeepPLTR model considers pairs of books and learns to assign a higher score to the one that better matches the customer query.

The DeepPLTR model’s architecture consists of three specialized towers. The left tower factors in contextual features and recent search patterns using a long-short-term-memory model, which processes data sequentially and considers its prior decisions when issuing a new term in the sequence. The middle tower handles keyword and item engagement history. The right tower factors in customer taste preferences and product descriptions to enable personalization. The model learns from paired examples, but at runtime, it relies on books’ absolute scores to assemble a ranked list.

Training architecture of the DeepPLTR model, which takes in paired examples (green and pink blocks). At runtime, the model scores only a single candidate at a time.

For Amazon, we implemented a two-stage modeling approach involving a probabilistic information-retrieval model to determine the book title that best matches each keyword and a second model that personalizes the book format (audiobooks, e-books, and physical books). This dual-strategy approach maintains low latency while still enabling personalization.

In practice, a customer who types “dungeon craw” in the search bar now sees a visual recommendation for the book Dungeon Crawler Carl, complete with book cover, reducing friction by bypassing a search results page and sending the customer directly to the product detail page. On Audible, the system also personalizes autocomplete results and enriches the discovery experience with relevant connections. These include links to the author’s complete works (Matt Dinniman’s author page) and, for titles that belong to a series, links to the full collection (such as the Dungeon Crawler Carl series).

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Using reinforcement learning improves candidate selection and ranking for search, ad platforms, and recommender systems.

On Amazon, when the customer clicks on the title, the model personalizes the right book-format (audiobooks, e-books, physical books) recommendation and directs the customer to the right product detail page.

In both cases, after the customer has entered a certain number of keystrokes, the system employs a model to detect customer intent (e.g., book title intent for Amazon or author intent for Audible) and determine which visual widget should be displayed.

Audible and Amazon books’ visual autocomplete provides customers with more relevant content more rapidly than traditional autocomplete, and its direct navigation reduces the number of steps to find and access desired books — all while handling millions of queries at low latency.

This technology is not just about making book discovery easier; it is laying the foundation for future improvements in search personalization and visual discovery across Amazon’s ecosystem.

Acknowledgements: Jiun Kim, Sumit Khetan, Armen Stepanyan, Jack Xuan, Nathan Brothers, Eddie Chen, Vincent Lee, Soumy Ladha, Justine Luo, Yuchen Zeng, David Torres, Gali Deutsch, Chaitra Ramdas, Christopher Gomez, Sharmila Tamby, Melissa Ma, Cheng Luo, Jeffrey Jiang, Pavel Fedorov, Ronald Denaux, Aishwarya Vasanth, Azad Bajaj, Mary Heer, Adam Lowe, Jenny Wang, Cameron Cramer, Emmanuel Ankrah, Lydia Diaz, Suzette Islam, Fei Gu, Phil Weaver, Huan Xue, Kimmy Dai, Evangeline Yang, Chao Zhu, Anvy Tran, Jessica Wu, Xiaoxiong Huang, Jiushan Yang





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Revolutionizing warehouse automation with scientific simulation

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Modern warehouses rely on complex networks of sensors to enable safe and efficient operations. These sensors must detect everything from packages and containers to robots and vehicles, often in changing environments with varying lighting conditions. More important for Amazon, we need to be able to detect barcodes in an efficient way.

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Generative AI supports the creation, at scale, of complex, realistic driving scenarios that can be directed to specific locations and environments.

The Amazon Robotics ID (ARID) team focuses on solving this problem. When we first started working on it, we faced a significant bottleneck: optimizing sensor placement required weeks or months of physical prototyping and real-world testing, severely limiting our ability to explore innovative solutions.

To transform this process, we developed Sensor Workbench (SWB), a sensor simulation platform built on NVIDIA’s Isaac Sim that combines parallel processing, physics-based sensor modeling, and high-fidelity 3-D environments. By providing virtual testing environments that mirror real-world conditions with unprecedented accuracy, SWB allows our teams to explore hundreds of configurations in the same amount of time it previously took to test just a few physical setups.

Camera and target selection/positioning

Sensor Workbench users can select different cameras and targets and position them in 3-D space to receive real-time feedback on barcode decodability.

Three key innovations enabled SWB: a specialized parallel-computing architecture that performs simulation tasks across the GPU; a custom CAD-to-OpenUSD (Universal Scene Description) pipeline; and the use of OpenUSD as the ground truth throughout the simulation process.

Parallel-computing architecture

Our parallel-processing pipeline leverages NVIDIA’s Warp library with custom computation kernels to maximize GPU utilization. By maintaining 3-D objects persistently in GPU memory and updating transforms only when objects move, we eliminate redundant data transfers. We also perform computations only when needed — when, for instance, a sensor parameter changes, or something moves. By these means, we achieve real-time performance.

Visualization methods

Sensor Workbench users can pick sphere- or plane-based visualizations, to see how the positions and rotations of individual barcodes affect performance.

This architecture allows us to perform complex calculations for multiple sensors simultaneously, enabling instant feedback in the form of immersive 3-D visuals. Those visuals represent metrics that barcode-detection machine-learning models need to work, as teams adjust sensor positions and parameters in the environment.

CAD to USD

Our second innovation involved developing a custom CAD-to-OpenUSD pipeline that automatically converts detailed warehouse models into optimized 3-D assets. Our CAD-to-USD conversion pipeline replicates the structure and content of models created in the modeling program SolidWorks with a 1:1 mapping. We start by extracting essential data — including world transforms, mesh geometry, material properties, and joint information — from the CAD file. The full assembly-and-part hierarchy is preserved so that the resulting USD stage mirrors the CAD tree structure exactly.

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Two Alexa AI papers present novel methodologies that use vision and language understanding to improve embodied task completion in simulated environments.

To ensure modularity and maintainability, we organize the data into separate USD layers covering mesh, materials, joints, and transforms. This layered approach ensures that the converted USD file faithfully retains the asset structure, geometry, and visual fidelity of the original CAD model, enabling accurate and scalable integration for real-time visualization, simulation, and collaboration.

OpenUSD as ground truth

The third important factor was our novel approach to using OpenUSD as the ground truth throughout the entire simulation process. We developed custom schemas that extend beyond basic 3-D-asset information to include enriched environment descriptions and simulation parameters. Our system continuously records all scene activities — from sensor positions and orientations to object movements and parameter changes — directly into the USD stage in real time. We even maintain user interface elements and their states within USD, enabling us to restore not just the simulation configuration but the complete user interface state as well.

This architecture ensures that when USD initial configurations change, the simulation automatically adapts without requiring modifications to the core software. By maintaining this live synchronization between the simulation state and the USD representation, we create a reliable source of truth that captures the complete state of the simulation environment, allowing users to save and re-create simulation configurations exactly as needed. The interfaces simply reflect the state of the world, creating a flexible and maintainable system that can evolve with our needs.

Application

With SWB, our teams can now rapidly evaluate sensor mounting positions and verify overall concepts in a fraction of the time previously required. More importantly, SWB has become a powerful platform for cross-functional collaboration, allowing engineers, scientists, and operational teams to work together in real time, visualizing and adjusting sensor configurations while immediately seeing the impact of their changes and sharing their results with each other.

New perspectives

In projection mode, an explicit target is not needed. Instead, Sensor Workbench uses the whole environment as a target, projecting rays from the camera to identify locations for barcode placement. Users can also switch between a comprehensive three-quarters view and the perspectives of individual cameras.

Due to the initial success in simulating barcode-reading scenarios, we have expanded SWB’s capabilities to incorporate high-fidelity lighting simulations. This allows teams to iterate on new baffle and light designs, further optimizing the conditions for reliable barcode detection, while ensuring that lighting conditions are safe for human eyes, too. Teams can now explore various lighting conditions, target positions, and sensor configurations simultaneously, gleaning insights that would take months to accumulate through traditional testing methods.

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Amazon researchers draw inspiration from finite-volume methods and adapt neural operators to enforce conservation laws and boundary conditions in deep-learning models of physical systems.

Looking ahead, we are working on several exciting enhancements to the system. Our current focus is on integrating more-advanced sensor simulations that combine analytical models with real-world measurement feedback from the ARID team, further increasing the system’s accuracy and practical utility. We are also exploring the use of AI to suggest optimal sensor placements for new station designs, which could potentially identify novel configurations that users of the tool might not consider.

Additionally, we are looking to expand the system to serve as a comprehensive synthetic-data generation platform. This will go beyond just simulating barcode-detection scenarios, providing a full digital environment for testing sensors and algorithms. This capability will let teams validate and train their systems using diverse, automatically generated datasets that capture the full range of conditions they might encounter in real-world operations.

By combining advanced scientific computing with practical industrial applications, SWB represents a significant step forward in warehouse automation development. The platform demonstrates how sophisticated simulation tools can dramatically accelerate innovation in complex industrial systems. As we continue to enhance the system with new capabilities, we are excited about its potential to further transform and set new standards for warehouse automation.





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