Generation of citation-backed reports is a primary use case for retrieval-augmented generation (RAG) systems. While open-source evaluation tools exist for various RAG tasks, tools designed for report generation are lacking. Accordingly, we introduce Auto-ARGUE, a robust LLM-based implementation of the recently proposed ARGUE framework for report generation evaluation. We present analysis of Auto-ARGUE on the report generation pilot task from the TREC 2024 NeuCLIR track and on two tasks from the TREC 2024 RAG track, showing good system-level correlations with human judgments. Additionally, we release ARGUE-viz, a web app for visualization and fine-grained analysis of Auto-ARGUE judgments and scores1.

While ColBERT is an effective neural retrieval architecture, it requires a heavy index structure to support candidate set retrieval based on approximated token embeddings, gathering and decompressing document token embeddings, and applying the MaxSim operation. Indexes in PLAID and similar ColBERT implementations require five to ten times the disk storage of the original raw text, which limits their scalability. Furthermore, prior work has identified that the gathering and decompression stages are the primary inefficiencies at query time. Limiting the number of document tokens that must be gathered by thresholding and score approximation does not eliminate the need for the entire index to support ad hoc queries. In this work, we propose an embedding quantization approach that turns a ColBERT index into a true inverted index. We show that, theoretically, ColBERT with embedding quantization is equivalent to learned-sparse retrieval except for the scoring mechanism. Empirically, we demonstrate that our index is 50-70% smaller than a one-bit PLAID index while retaining retrieval effectiveness.

Multilingual retrieval has become a core functionality in information systems, such as retrieval-augmented generation, since the retrieved document can be post-processed by a large language model into a form that the users can easily consume. Whether the user can directly read the source documents becomes less vital to the search process. However, ad hoc retrieval has primarily been developed in English, limiting the capability of these complex systems to retrieve information across different languages. To address this challenge, we introduce a multilingual retrieval task at WSDM Cup 2026 that requires systems to search a multilingual collection using English queries.

Large language models (LLMs) can be effective at retrieval but are generally too expensive to use as first-stage rankers.As a consequence, several approaches to their use as rerankers of less expensive first-stage retrieval results have been suggested.Zhuang et al. recommend setwise approaches.In particular, they use heapsort to efficiently return top-ranked documents by obtaining a partial order from each LLM call.Utilizing rerankers requires setting parameters such as number of input documents, number of documents to be reranked, evaluation depth, number of tokens per document, and selection of LLM, all of which contribute to latency and effectiveness.In this work, we reproduce the batching and reranking of Zhuang et al. with a larger comparison window size.Furthermore, we determine that the document truncation used in the original implementation is suboptimal.By providing more context to the LLM, we show that the reranker is more effective than originally reported.

Most pretrained language models that support neural information retrieval are fine-tuned on the MS MARCO dataset.MS MARCO is expressed in English, so it naturally supports monolingual English retrieval.However, for Cross-Language Information Retrieval (CLIR), no similar training data naturally exists that matches the languages of the query and the documents.The main ways to address this problem have been to continue to fine-tune with English data, or to translate MS MARCO queries and/or documents to match the CLIR setting.Machine translation often introduces errors that reduce retrieval effectiveness.It is usually easy to find target language documents suitable for training, but difficult to find naturally-occurring queries in the query language.An alternative is to train on naturally-occurring documents and syntheticallygenerated queries.Generate-Distill uses this approach with stateof-the-art distillation methods to match the effectiveness of training with translated MS MARCO across different domains.

Recent work has shown that Large Language Models (LLMs) can produce relevance judgements for English retrieval that are useful as a basis for system comparison, and they do so at vastly reduced cost compared to human assessors. Using relevance judgements and ranked retrieval runs from the TREC NeuCLIR track, this paper shows that LLMs can also produce reliable assessments in other languages, even when the topic description or the prompt are in a language different from the documents. Results with Chinese, Persian and Russian documents show that although document language affects both agreement with human assessors on graded relevance and on preference ordering among systems, prompt-language and topic-language effects are negligible. This has implications for the design of multilingual test collections, suggesting that prompts and topic descriptions can be developed in any convenient language.

Retrieval-augmented generation (RAG) summarizes retrieved documents into a text passage that fulfills the information need expressed by the user. Such generated responses should faithfully distill the relevant information and provide sufficient attribution back to the source documents. Nugget-based evaluation was proposed for text summarization and has been adapted to evaluate RAG output in recent shared tasks such as 2024 TREC RAG, BioGen, and NeuCLIR tracks. However, annotating such detailed and nuanced information is complex and errorful. Multiple pieces of information need to be labeled, extracted, linked, and cross-referenced. In this work, we present an annotation protocol and tool tailored to collecting information for evaluating RAG systems. Our tool has four steps: nugget creation, nugget revision, document support assessment, and finally, nugget alignment. Each step aims to minimize the annotator's cognitive load, improving the efficiency and reliability.

PLAID, an efficient implementation of the ColBERT late interaction bi-encoder using pretrained language models for ranking, consistently achieves state-of-the-art performance in monolingual, cross-language, and multilingual retrieval. PLAID differs from ColBERT by assigning terms to clusters and representing those terms as cluster centroids plus compressed residual vectors. While PLAID is effective in batch experiments, its performance degrades in streaming settings where documents arrive over time because representations of new tokens may be poorly modeled by the earlier tokens used to select cluster centroids. PLAID Streaming Hierarchical Indexing that Runs on Terabytes of Temporal Text (PLAID HIRTTT) addresses this concern using multi-phase incremental indexing based on hierarchical sharding. Experiments on ClueWeb09 and the multilingual NeuCLIR collection demonstrate the effectiveness of this approach both for the largest collection indexed to date by the ColBERT architecture and in the multilingual setting, respectively.

Large Language Models (LLMs) have enabled new ways to satisfy information needs. Although great strides have been made in applying them to settings like document ranking and short-form text generation, they still struggle to compose complete, accurate, and verifiable long-form reports. Reports with these qualities are necessary to satisfy the complex, nuanced, or multi-faceted information needs of users. In this perspective paper, we draw together opinions from industry and academia, and from a variety of related research areas, to present our vision for automatic report generation, and---critically---a flexible framework by which such reports can be evaluated. In contrast with other summarization tasks, automatic report generation starts with a detailed description of an information need, stating the necessary background, requirements, and scope of the report. Further, the generated reports should be complete, accurate, and verifiable. These qualities, which are desirable---if not required---in many analytic report-writing settings, require rethinking how to build and evaluate systems that exhibit these qualities. To foster new efforts in building these systems, we present an evaluation framework that draws on ideas found in various evaluations. To test completeness and accuracy, the framework uses nuggets of information, expressed as questions and answers, that need to be part of any high-quality generated report. Additionally, evaluation of citations that map claims made in the report to their source documents ensures verifiability.

Multilingual information retrieval (MLIR) considers the problem of ranking documents in several languages for a query expressed in a language that may differ from any of those languages. Recent work has observed that approaches such as combining ranked lists representing a single document language each or using multilingual pretrained language models demonstrate a preference for one language over others. This results in systematic unfair treatment of documents in different languages. This work proposes a language fairness metric to evaluate whether documents across different languages are fairly ranked through statistical equivalence testing using the Kruskal-Wallis test. In contrast to most prior work in group fairness, we do not consider any language to be an unprotected group. Thus our proposed measure, PEER (Probability of Equal Expected Rank), is the first fairness metric specifically designed to capture the language fairness of MLIR systems. We demonstrate the behavior of PEER on artificial ranked lists. We also evaluate real MLIR systems on two publicly available benchmarks and show that the PEER scores align with prior analytical findings on MLIR fairness. Our implementation is compatible with ir-measures and is available at http://github.com/hltcoe/peer_measure.

Recent work in cross-language information retrieval (CLIR), where queries and documents are in different languages, has shown the benefit of the Translate-Distill framework that trains a cross-language neural dual-encoder model using translation and distillation. However, Translate-Distill only supports a single document language. Multilingual information retrieval (MLIR), which ranks a multilingual document collection, is harder to train than CLIR because the model must assign comparable relevance scores to documents in different languages. This work extends Translate-Distill and propose Multilingual Translate-Distill (MTD) for MLIR. We show that ColBERT-X models trained with MTD outperform their counterparts trained with Multilingual Translate-Train, which is the previous state-of-the-art training approach, by 5% to 25% in nDCG@20 and 15% to 45% in MAP. We also show that the model is robust to the way languages are mixed in training batches. Our implementation is available on GitHub.

While there are many test collections for Cross-Language Information Retrieval (CLIR), none of the large public test collections focus on short informal text documents. This paper introduces a new pair of CLIR test collections with millions of Chinese or Persian Tweets or Tweet threads as documents, sixty event-motivated topics written both in English and in each of the two document languages, and three-point graded relevance judgments constructed using interactive search and active learning. The design and construction of these new test collections are described, and baseline results are presented that demonstrate the utility of the collections for system evaluation. Shallow pooling is used to assess the efficacy of active learning to select documents for judgment.

Learning sparse representations using pretrained language models enhances the monolingual ranking effectiveness. Such representations are sparse vectors in the vocabulary of a language model projected from document terms. Extending such approaches to Cross-Language Information Retrieval (CLIR) using multilingual pretrained language models poses two challenges. First, the larger vocabularies of multilingual models affect both training and inference efficiency. Second, the representations of terms from different languages with similar meanings might not be sufficiently similar. To address these issues, we propose a learned sparse representation model, BLADE, combining vocabulary pruning with intermediate pre-training based on cross-language supervision. Our experiments reveal BLADE significantly reduces indexing time compared to its monolingual counterpart, SPLADE, on machine-translated documents, and it generates rankings with strengths complementary to those of other efficient CLIR methods.

This half day tutorial introduces the participant to the basic concepts underlying neural Cross-Language Information Retrieval (CLIR). It discusses the most common algorithmic approaches to CLIR, focusing on modern neural methods; the history of CLIR; where to find and how to use CLIR training collections, test collections and baseline systems; how CLIR training and test collections are constructed; and open research questions in CLIR.

Studying the effects of semantic analysis on retrieval effectiveness can be difficult using standard test collections because both queries and documents typically lack semantic markup. This paper describes extensions to two test collections, CLEF 2003/2004 Russian and TDT-3 Chinese, to support study of the utility of named entity annotation. A new set of topic aspects that were expected to benefit from named entity markup were defined for topics in those test collections, with two queries for each aspect. One of these queries uses named entities as bag-of-words query terms or as semantic constraints on a free-text query term; the other is a bag-of-words baseline query without named entity markup. Exhaustive judgment of the documents annotated by CLEF or TDT as relevant to each corresponding topic was performed, resulting in relevance judgments for 133 Russian and 33 Chinese topic aspects that each have at least one relevant document. Named entity tags were automatically generated for the documents in both collections. Use of the test collections is illustrated with some preliminary experiments.

The goal of entity linking is to associate references to an entity that is found in unstructured natural language content to an authoritative inventory of known entities. This article describes the construction of 6 test collections for cross‐language person‐entity linking that together span 22 languages. Fully automated components were used together with 2 crowdsourced validation stages to affordably generate ground‐truth annotations with an accuracy comparable to that of a completely manual process. The resulting test collections each contain between 642 (Arabic) and 2,361 (Romanian) person references in non‐English texts for which the correct resolution in English Wikipedia is known, plus a similar number of references for which no correct resolution into English Wikipedia is believed to exist. Fully automated cross‐language person‐name linking experiments with 20 non‐English languages yielded a resolution accuracy of between 0.84 (Serbian) and 0.98 (Romanian), which compares favorably with previously reported cross‐language entity linking results for Spanish.

The selection of indexing terms for representing documents is a key decision that limits how effective subsequent retrieval can be. Often stemming algorithms are used to normalize surface forms, and thereby address the problem of not finding documents that contain words related to query terms through infectional or derivational morphology. However, rule-based stemmers are not available for every language and it is unclear which methods for coping with morphology are most effective. In this paper we investigate an assortment of techniques for representing text and compare these approaches using data sets in eighteen languages and five different writing systems.

The choice of indexing terms used to represent documents crucially determines how e ective subsequent retrieval will be. IR systems commonly use rule-based stemmers to normalize surface word forms to combat the problem of not finding documents that contain words related to query terms by inflectional or derivational morphology. But such stemmers are not available in all languages. In this paper we explore the effectiveness of unsupervised morphological segmentation as an alternative to stemming using test sets in thirteen European languages. We find that unsupervised segmentation is significantly better than unnormalized words, in several cases by more than 20%. However, rule-based stemming, if available, is better in low complexity languages. We also compare these methods to the use of character n-grams, finding that on average n-grams yield the best performance.

We present a simple way to improve document retrieval for question answering systems. The method biases the retrieval system toward documents that contain words that have appeared in other documents containing answers to the same type of question. The method works with virtually any retrieval system, and exhibits a statistically significant performance improvement over a strong baseline.

Translation for cross-language information retrieval need not be word-based. We show that character n-grams in one language can be 'translated' into character n-grams of another language. We demonstrate that such translations produce retrieval results on par with, and often exceeding, those of word-based and stem-based translation.

Transitive retrieval and triangulation have been proposed as ways to improve cross-language retrieval quality when translation resources have poor lexical coverage. We demonstrate that cross-language retrieval is viable for European languages with no translation resources at all; that transitive retrieval without translation does not suffer the drop-off in retrieval quality sometimes reported for transitive retrieval with translation; and that triangulation that combines multiple transitive runs with no translation can boost performance over direct translation-free retrieval.

Test collections model use cases in ways that facilitate evaluation of information retrieval systems. This paper describes the use of search-guided relevance assessment to create a test collection for retrieval of spontaneous conversational speech. Approximately 10,000 thematically coherent segments were manually identified in 625 hours of oral history interviews with 246 individuals. Automatic speech recognition results, manually prepared summaries, controlled vocabulary indexing, and name authority control are available for every segment. Those features were leveraged by a team of four relevance assessors to identify topically relevant segments for 28 topics developed from actual user requests. Search-guided assessment yielded sufficient inter-annotator agreement to support formative evaluation during system development. Baseline results for ranked retrieval are presented to illustrate use of the collection.

Tagging algorithms have become increasingly important for identifying lexical and semantic features of unstructured text. We describe an approach to lattice-based tagging that estimates joint transition and emission probabilities using support vector machines. The technique offers several advantages over alternative methods, including the ability to accommodate non-local features, support for hundreds of thousands of features, and language-neutrality. We demonstrate the technique on two tagging applications: named entity recognition and part-of-speech tagging.

Stemming can improve retrieval accuracy, but stemmers are language-specific. Character n-gram tokenization achieves many of the benefits of stemming in a language independent way, but its use incurs a performance penalty. We demonstrate that selection of a single n-gram as a pseudo-stem for a word can be an effective and efficient language-neutral approach for some languages.

We describe a language called ABET that allows rapid conversion of on-line human-readable bilingual dictionaries to machinereadable form.

The quality of translation resources is arguably the most important factor affecting the performance of a cross-language information retrieval system. While many investigations have explored the use of query expansion techniques to combat errors induced by translation, no study has yet examined the effectiveness of these techniques across resources of varying quality. This paper presents results using parallel corpora and bilingual wordlists that have been deliberately degraded prior to query translation. Across different languages, translingual resources, and degrees of resource degradation, pre-translation query expansion is tremendously effective. In several instances, pre-translation expansion results in better performance when no translations are available, than when an uncompromised resource is used without pre-translation expansion. We also demonstrate that post-translation expansion using relevance feedback can confer modest performance gains. Measuring the efficacy of these techniques with resources of different quality suggests an explanation for the conflicting reports that have appeared in the literature.

A new model of hypertext, in which text is augmented with a fine-grained semantic net representation of the text, solves several problems found in traditional hypertext models. In the new model, hypertext links are paths that originate in the text, move across to the semantic net, traverse a sub-path through the semantic net, then return to a different point in the text. Benefits of the model include a strong semantics for links, dynamic discovery of links, link reusability, and automatic creation of links. The SNITCH hypertext system, which is based on this model, allows a user to access data in ways never foreseen by the hypertext author.