Algebraic Structure of Combined Traces

Traces and their extension called combined traces (comtraces) are two formal models used in the analysis and verification of concurrent systems. Both models are based on concepts originating in the theory of formal languages, and they are able to capture the notions of causality and simultaneity of atomic actions which take place during the process of a system's operation. The aim of this paper is a transfer to the domain of comtraces and developing of some fundamental notions, which proved to be successful in the theory of traces. In particular, we introduce and then apply the notion of indivisible steps, the lexicographical canonical form of comtraces, as well as the representation of a comtrace utilising its linear projections to binary action subalphabets. We also provide two algorithms related to the new notions. Using them, one can solve, in an efficient way, the problem of step sequence equivalence in the context of comtraces. One may view our results as a first step towards the development of infinite combined traces, as well as recognisable languages of combined traces.Comment: Short variant of this paper, with no proofs, appeared in Proceedings of CONCUR 2012 conferenc

Lifting connections to the r-jet prolongation of the cotangent bundle

We show that the problem of finding all Mfm -natural operators C : Q "M QJ r T ∗ lifting classical linear connections ∇ on m-manifolds M into classical linear connections CM (∇) on the r-jet prolongation J r T ∗M of the cotangent bundle T ∗M p of M can be reduced to that of finding all Mfm -natural operators D : Q "M® T ⊗ q ® T ∗ sending classical linear connections ∇ on M into tensor fields DM (∇) of type (p, q) on M

The natural brackets on couples of vector fields and 1-forms

All natural bilinear operators transforming pairs of couples of vector fields and 1-forms into couples of vector fields and 1-forms are found. All natural bilinear operators as above satisfying the Leibniz rule are extracted. All natural Lie algebra brackets on couples of vector fields and 1-forms are collected

Koszty działalności szpitala jako główny składnik cenowej formuły usług zdrowotnych

Zadanie pt. „Digitalizacja i udostępnienie w Cyfrowym Repozytorium Uniwersytetu Łódzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet Łódzki” nr 885/P-DUN/2014 dofinansowane zostało ze środków MNiSW w ramach działalności upowszechniającej naukę

Transposition Rearrangement: Linear Algorithm for Length-Cost Model

The contemporary computational biology gives motivation to study dependencies between finite sequences. Primary structures of DNA or proteins are represented by such sequences (also called words or strings). In the paper a linear algorithm, computing the distance between two words, is presented. The model operates with transpositions of single letters. The cost of a single transposition is equal to the distance which transposed letter has to cover. Other papers concerning the model give, as the best known, algorithms of time complexity O(n log n). The complexity of our algorithm is O(nk), where k is the size of the alphabet, and O(n) when the size is fixed