Position Bias Estimation for Unbiased Learning-to-Rank in eCommerce Search

The Unbiased Learning-to-Rank framework has been recently proposed as a general approach to systematically remove biases, such as position bias, from learning-to-rank models. The method takes two steps - estimating click propensities and using them to train unbiased models. Most common methods proposed in the literature for estimating propensities involve some degree of intervention in the live search engine. An alternative approach proposed recently uses an Expectation Maximization (EM) algorithm to estimate propensities by using ranking features for estimating relevances. In this work we propose a novel method to directly estimate propensities which does not use any intervention in live search or rely on modeling relevance. Rather, we take advantage of the fact that the same query-document pair may naturally change ranks over time. This typically occurs for eCommerce search because of change of popularity of items over time, existence of time dependent ranking features, or addition or removal of items to the index (an item getting sold or a new item being listed). However, our method is general and can be applied to any search engine for which the rank of the same document may naturally change over time for the same query. We derive a simple likelihood function that depends on propensities only, and by maximizing the likelihood we are able to get estimates of the propensities. We apply this method to eBay search data to estimate click propensities for web and mobile search and compare these with estimates using the EM method. We also use simulated data to show that the method gives reliable estimates of the "true" simulated propensities. Finally, we train an unbiased learning-to-rank model for eBay search using the estimated propensities and show that it outperforms both baselines - one without position bias correction and one with position bias correction using the EM method.Comment: 10 pages, 3 figure

ПРАВОВЫЕ ПРОБЛЕМЫ УСТАНОВЛЕНИЯ СУБЪЕКТАМИ РОССИЙСКОЙ ФЕДЕРАЦИИ ДОПОЛНИТЕЛЬНЫХ ГАРАНТИЙ РЕАЛИЗАЦИИ КОНСТИТУЦИОННЫХ ПРАВ И СВОБОД ЧЕЛОВЕКА И ГРАЖДАНИНА

The subject. The article focuses on the need to improve legislative and law enforcement activities related to the consolidation of constituent entities of the Russian Federation additional guarantees of realization of constitutional human and civil rights and freedoms.The purpose of the article is to identify main ways of improvement the legal regulation additional guarantees of realization of constitutional human and civil rights and freedoms by the constituent entities of the Russian Federation.The methodology. The author uses a dialectical method, a method of analysis and synthesis, a formal legal method.The results and scope of application. The lack of unity in understanding the essence of additional guarantees of realization of rights and freedoms requires not only theoretical analysis of this legal category, but a consistent system of the legislation, and corresponding to the system of law enforcement practice. The legal establishment of the additional guarantees of realization of constitutional human and civil rights and freedoms, due solely to the will of the legislator of a constituent entitiy of the Russian Federation aimed at the concretization of constitutional rights and freedoms as well as of the security mechanisms (legal conditions, means) of the implementation of these rights. Features of development of the corresponding constituent entitiy of the Russian Federation should be taken into account.One of the main directions of improvement of legal regulation in this field is legislative recognition of additional guarantees of realization of constitutional human and civil rights and freedoms established by the constituent entities of the Russian Federation. This concept should be reflected in the Federal law of October 6, 1999 No. 184-FZ "On General principles of organization of legislative (representative) and executive bodies of state power of constituent entities of the Russian Federation", as well as in the constitutions (charters) of constituent entities of the Russian Federation. The consolidation of this concept in the legislation will be the impetus to the theoretical analysis of this legal category, and will ultimately contribute to the improvement of the legal status of the individual.Conclusions. Improvement of regional legal policy in the sphere of establishment additional guarantees of realization of constitutional human and civil rights and freedoms by subjects of the Russian Federation has great practical significance and contributes to the theoretical knowledge of the specified legal category.Акцентируется внимание на необходимости совершенствования законодательной и правоприменительной деятельности, связанной с закреплением субъектами Российской Федерации дополнительных гарантий реализации конституционных прав и свобод человека и гражданина. Определяются направления совершенствования правового регулирования в области установления субъектами Российской Федерации дополнительных гарантий реализации конституционных прав и свобод человека и гражданина. Делается вывод, что совершенствование региональной правовой политики в области закрепления субъектами Российской Федерации дополнительных гарантий реализации конституционных прав и свобод человека и гражданина имеет огромную практическую значимость и способствует теоретическому познанию указанной правовой категории

Конституционно-правовые основы единой системы публичной власти в Российской Федерации (региональный аспект)

Within the framework of this study, theoretical approaches to understanding public power in the context of various areas of scientific knowledge are analyzed. In the course of this work, attention is drawn to the constitutional approach, according to which the unified system of public power in the Russian Federation includes two independent, but interacting levels: state and municipal. In this regard, it is noted that the federal legislation adopted in the development of constitutional provisions significantly expands this approach and actually establishes a three-level system of public power. As a consequence, the problem of substantiating the existence of a unified system of public power in the subjects of the Russian Federation is being actualized. Using the system-logical method of research, the provisions of Federal Law No. 414-FZ of December 21, 2021 "On the general principles of the organization of public power in the Subjects of the Russian Federation", which normatively establish the category of a unified system of public power in the subject of the Russian Federation, are analyzed in the work. Certain provisions of the said federal law are not fully consistent with each other and with other federal legislation, including with regard to the constitutional and legal understanding of the unified system of public power. At the same time, attention is drawn to the fact that the territorial principle cannot underlie the allocation of an independent regional level of public power, since the derivation of public power from the understanding of "state" and "statehood", on the basis of equality of the subjects of the Russian Federation as a constitutional principle, makes it impossible to have a different ratio of intra-system connections in the systems of public power in the subjects of the Russian Federation. The formal legal approach made it possible to trace the dynamics of changes in the constitutional (statutory) legislation of the subjects of the Russian Federation, depending on the understanding of the place of state authorities of the subjects of the Russian Federation in the unified system of public power. Various normative variations of the constitutional (statutory) legislation of the subjects of the Russian Federation, aimed at bringing it into line with the same constitutional text, indicates the absence of an unambiguous and uniform understanding of the place of the system of state authorities of the subjects of the Russian Federation in the unified system of public power in the country. Thus, it is noted that the development of a uniform approach based on the positions of the Constitutional Court of the Russian Federation, which are mandatory for all subjects of legislative activity, to the content of the category "unified system of public power in the Russian Federation" is fully capable of ensuring the goal of its formation stated in Part 3 of Article 132 of the Constitution of the Russian Federation in compliance with all constitutional principles and norms. In this regard, within the framework of the unified system of public power in Russia, we should not talk about independent unified systems of public power in the subjects of the Russian Federation, but should focus on the formation of a unified system of public power throughout the territory of our state.Характеристика современных подходов к пониманию единой системы публичной власти в нашей стране с точки зрения ее содержательной и уровневой составляющей не позволяет вести речь об однообразии взглядов, позиций и понимания данной правовой конструкции как на уровне доктринальных исследований, так и на уровне правотворчества. Проблема усугубляется и тем фактом, что федеральный законодатель, развивая нормативные основы единой системы публичной власти на уровне отдельных федеральных законов, существенным образом расширяет конституционно установленные границы этой системы, во многом не учитывая уже ранее высказанные правовые позиции Конституционного Суда РФ о конституционно-правовой сущности публичной власти. В рамках настоящего исследования предпринята попытка аргументировать необходимость установить соотношения конституционных принципов «единой системы государственной власти» и «единой системы публичной власти» с позиции философских категорий целого и части, что способствует пониманию системы органов публичной власти в субъекте Российской Федерации как составляющей единственно существующей системы государственной власти в Российской Федерации, которая, в свою очередь, является частью создаваемой в России наряду с органами местного самоуправления единой системы публичной власти

Attentive History Selection for Conversational Question Answering

Conversational question answering (ConvQA) is a simplified but concrete setting of conversational search. One of its major challenges is to leverage the conversation history to understand and answer the current question. In this work, we propose a novel solution for ConvQA that involves three aspects. First, we propose a positional history answer embedding method to encode conversation history with position information using BERT in a natural way. BERT is a powerful technique for text representation. Second, we design a history attention mechanism (HAM) to conduct a "soft selection" for conversation histories. This method attends to history turns with different weights based on how helpful they are on answering the current question. Third, in addition to handling conversation history, we take advantage of multi-task learning (MTL) to do answer prediction along with another essential conversation task (dialog act prediction) using a uniform model architecture. MTL is able to learn more expressive and generic representations to improve the performance of ConvQA. We demonstrate the effectiveness of our model with extensive experimental evaluations on QuAC, a large-scale ConvQA dataset. We show that position information plays an important role in conversation history modeling. We also visualize the history attention and provide new insights into conversation history understanding.Comment: Accepted to CIKM 201

Evaluating intuitiveness of vertical-aware click models

Modeling user behavior on a search engine result page is important for understanding the users and supporting simulation experiments. As result pages become more complex, click models evolve as well in order to capture additional aspects of user behavior in response to new forms of result presentation. We propose a method for evaluating the intuitiveness of vertical-aware click models, namely the ability of a click model to capture key aspects of aggregated result pages, such as vertical selection, item selection, result presentation and vertical diversity. This method allows us to isolate model components and therefore gives a multi-faceted view on a model's performance. We argue that our method can be used in conjunction with traditional click model evaluation metrics such as log-likelihood or perplexity. In order to demonstrate the power of our method in situations where result pages can contain more than one type of vertical(e.g., Image and News) we extend the previously studied Federated Click Model such that it models user clicks on such pages. Our evaluation method yields non-trivial yet interpretable conclusions about the intuitiveness of click models, highlighting their strengths and weaknesses

Open-Retrieval Conversational Question Answering

Conversational search is one of the ultimate goals of information retrieval. Recent research approaches conversational search by simplified settings of response ranking and conversational question answering, where an answer is either selected from a given candidate set or extracted from a given passage. These simplifications neglect the fundamental role of retrieval in conversational search. To address this limitation, we introduce an open-retrieval conversational question answering (ORConvQA) setting, where we learn to retrieve evidence from a large collection before extracting answers, as a further step towards building functional conversational search systems. We create a dataset, OR-QuAC, to facilitate research on ORConvQA. We build an end-to-end system for ORConvQA, featuring a retriever, a reranker, and a reader that are all based on Transformers. Our extensive experiments on OR-QuAC demonstrate that a learnable retriever is crucial for ORConvQA. We further show that our system can make a substantial improvement when we enable history modeling in all system components. Moreover, we show that the reranker component contributes to the model performance by providing a regularization effect. Finally, further in-depth analyses are performed to provide new insights into ORConvQA.Comment: Accepted to SIGIR'2

Standing stock of Antarctic krill (Euphausia superba Dana, 1850) (Euphausiacea) in the Southwest Atlantic sector of the Southern Ocean, 2018–19

Estimates of the distribution and density of Antarctic krill (Euphausia superba Dana, 1850) were derived from a large-scale survey conducted during the austral summer in the Southwest Atlantic sector of the Southern Ocean and across the Scotia Sea in 2018–19, the ‘2018–19 Area 48 Survey’. Survey vessels were provided by Norway, the Association of Responsible Krill harvesting companies and Aker BioMarine AS, the United Kingdom, Ukraine, Republic of Korea, and China. Survey design followed the transects of the Commission for the Conservation of Antarctic Marine Living Resources synoptic survey, carried out in 2000 and from regular national surveys performed in the South Atlantic sector by the U.S., China, Republic of Korea, Norway, and the U.K. The 2018–19 Area 48 Survey represents only the second large-scale survey performed in the area and this joint effort resulted in the largest ever total transect line (19,500 km) coverage carried out as one single exercise in the Southern Ocean. We delineated and integrated acoustic backscatter arising from krill swarms to produce distribution maps of krill areal biomass density and standing stock (biomass) estimates. Krill standing stock for the Area 48 was estimated to be 62.6 megatonnes (mean density of 30 g m–2 over 2 million km2) with a sampling coefficient variation of 13%. The highest mean krill densities were found in the South Orkney Islands stratum (93.2 g m–2) and the lowest in the South Georgia Island stratum (6.4 g m–2). The krill densities across the strata compared to those found during the previous survey indicate some regional differences in distribution and biomass. It is currently not possible to assign any such differences or lack of differences between the two survey datasets to longer term trends in the environment, krill stocks or fishing pressure