Center for Mathematics, Fundamental Applications and Operations Research

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Publications

A strategy to assess water meter performance

Publication . Cordeiro, Clara; Borges, Ana; Ramos, Maria do Rosário

Apparent water losses can be problematic to water companies’ revenues. This type of loss is very difficult to detect and quantify and is often associated with water meter anomalies. This study was motivated by a water company’s challenge that links a decrease in water consumption to water meters’ malfunction. The aim is to develop a strategy to detect decreasing water usage patterns, contributing to meter performance assessment. The basis of the approach is a combination of statistical methods. First, the time series of billed water consumption is decomposed using Seasonal-Trend decomposition based on Loess. Next, breakpoint analysis is performed on the seasonally adjusted time series. After that, the Mann–Kendall test and Sen’s slope estimator are used to analyze periods of progressive decrease changes in water consumption, defined by breakpoints. A quantitative indicator of this change is proposed. The strategy was successfully applied to eight-time series of water consumption from the Algarve, Portugal.

2021-11Journal article

Restricted access

Typability and type inference in atomic polymorphism

Publication . Protin, M. Clarence; Ferreira, Gilda

It is well-known that typability, type inhabitation and type inference are undecidable in the Girard-Reynolds polymorphic system F. It has recently been proven that type inhabitation remains undecidable even in the predicative fragment of system F in which all universal instantiations have an atomic witness (system Fat). In this paper we analyze typability and type inference in Curry style variants of system Fat and show that typability is decidable and that there is an algorithm for type inference which is capable of dealing with non-redundancy constraints.

2022Journal article

Open access

A matemática na sociedade europeia e a Sociedade Europeia de Matemática

Publication . Buescu, Jorge; Costa, Fernando Pestana da

Apresenta-se uma brevíssima panorâmica do surgimento e desenvolvimento da Matemática no espaço europeu, bem como uma breve referência às organizações científicas (academias e sociedades) relevantes para as ciências matemáticas na Europa, terminando com uma secção sobre a fundação e as atividades da Sociedade Europeia de Matemática (EMS), incluindo reminiscências sobre o papel da Sociedade Portuguesa de Matemática da autoria do representante de Portugal no ato fundador da EMS.

2025Journal article

Open access

Analysis on the cone of discrete Radon measures

Publication . Finkelshtein, Dmitri; Kondratiev, Yuri; Kuchling, Peter; Lytvynov, Eugene; Oliveira, Maria João

We study analysis on the cone of discrete Radon measures over a locally compact Polish space X. We discuss probability measures on the cone and the corresponding correlation measures and correlation functions on the sub-cone of finite discrete Radon measures over X. For this, we consider on the cone an analogue of the harmonic analysis on the configuration space developed in [Y. G. Kondratiev, T. Kuna, Harmonic analysis on configuration space. I. General theory, Infin. Dimens. Anal. Quantum Probab. Relat. Top. 5 (2002), 201–233.]. We also study elements of finite-difference calculus on the cone: we introduce discrete birth-and-death gradients and study the corresponding Dirichlet forms; finally, we discuss a system of polynomial functions on the cone which satisfy the binomial identity.

2025Journal article

Embargoed access

How to avoid the commuting conversions of IPC

Publication . Espírito Santo, José; Ferreira, Gilda

Since the observation in 2006 that it is possible to embed IPC into the atomic polymorphic λ-calculus (a predicative fragment of system F with universal instantiations restricted to atomic formulas) different such embeddings appeared in the literature. All of them comprise the Russell-Prawitz translation of formulas, but have different strategies for the translation of proofs. Although these embeddings preserve proof identity, all fail in delivering preservation of reduction steps. In fact, they translate the commuting conversions of IPC to β-equality, or to other kinds of reduction or equality generated by new principles added to system F. The cause for this is the generation of redexes by the translation itself. In this paper, we present an embedding of IPC into atomic system F, still based on the same translation of formulas, but which maps commuting conversions to syntactic identity, while simulating the other kinds of reduction steps present in IPC by βη-reduction. In this sense the translation achieves a truly commuting-conversion-free image of IPC in atomic system F.

2025-04-07Journal article

Open access