A study conducted by the International Data Corporation predicted that by the year 2021, the total amount of digital information resources would have reached the 40 zettabyte mark [2]. According to a rule formulated by Merrill Lynch, 80 to 90% of these resources are unstructured [7]. Despite this, users expect digital libraries to provide them with fast and interpretable access to digital information resources that will satisfy their information need. Math information retrieval emerged as a subfield of information retrieval in 2008 [8], when it became clear that standard information retrieval techniques used for text documents are inadequate to accurately retrieve documents in digital mathematical libraries.

The standard bag-of-words vector space model (VSM) is efficient, and ubiquitous in information retrieval, but it underestimates the similarity of documents with the same meaning, but different terminology. To overcome this limitation, Sidorov et al. proposed the Soft Cosine Measure (SCM) that incorporates term similarity relations. Charlet and Damnati showed that the SCM is highly effective in question answering (QA) systems. However, the orthonormalization algorithm proposed by Sidorov et al. has an impractical time complexity of O(n^4), where n is the size of the vocabulary. In this paper, we prove a tighter lower worst-case time complexity bound of O(n^3). We also present an algorithm for computing the similarity between documents and we show that its worst-case time complexity is O(1) given realistic conditions. Lastly, we describe implementation in general-purpose vector databases such as Annoy, and Faiss and in the inverted indices of text search engines such as Apache Lucene, and ElasticSearch. Our results enable the deployment of the SCM in real-world information retrieval systems.

Digital mathematical libraries (DMLs) such as arXiv, Numdam, and EuDML contain mainly documents from STEM fields, where mathematical formulae are often more important than text for understanding. Conventional information retrieval (IR) systems are unable to represent formulae and they are therefore ill-suited for math information retrieval (MIR). To fill the gap, we have developed, and open-sourced the MIaS MIR system. MIaS is based on the full-text search engine Apache Lucene. On top of text retrieval, MIaS also incorporates a set of tools for preprocessing mathematical formulae. We describe the design of the system and present speed, and quality evaluation results. We show that MIaS is both efficient, and effective, as evidenced by our victory in the NTCIR-11 Math-2 task.

As next-generation mobile networks are rapidly taking shape driven by the target standardization requirements and initial trial implementations, a range of accompanying technologies prepare to support them with more reliable wireless access and improved service provisioning. Among these are more advanced spectrum sharing options enabled by the emerging Licensed Shared Access (LSA) regulatory framework, which aims to efficiently employ the capacity of underutilized frequency bands in a controlled manner. The concept of LSA promises to equip network operators with the much needed additional spectrum on the secondary basis and thus brings changes to the existing cellular network management. Hence, additional research is in prompt demand to determine the required levels of Quality of Service (QoS) and service provisioning reliability, especially in cases of dynamic geographical and temporal LSA sharing. Motivated by this recent urge and having at our disposal a fully-functional 3GPP LTE cellular deployment, we have committed to implement and trial the principles of dynamic LSA-compatible spectrum management. This paper is our first disclosure on the comprehensive experimental evaluation of this promising technology. We expect that these unprecedented practical results together with the key lessons learned will become a valuable reference point for the subsequent integration of flexible LSA-based services, suitable for inter-operator and multi-tenant spectrum sharing.

In enterprise systems many software operations over a database are implemented in a similar way. Systems always take care of correct storage of a data into appropriate tables, data integrity, multilingual support, locales, data validation etc. Data are often stored in a relational database management systems using SQL. SQL standard itself does not provide suitable support for wide range of operations which need to be implemented in almost all cases. Furthermore SQL implementation and triggers/stored procedures programming language differ between various systems. This leads to very difficult migration of software systems based on one database management system to another. Access control provided by the databases is not suitable for an application because users would be allowed to access a database but they must be allowed to access an application instead. Sometimes an application needs to design a more sophisticated access control system. This article deals with this topic and designs an architecture which universally solves all mentioned problem areas. Key benefits it brings are independency on any particular database management system, easy migration to another one and fast fully automatic lowlevel record based rights checking.