A Diffie-Hellman based key management scheme for hierarchical access control

All organizations share data in a carefully managed fashion\ud by using access control mechanisms. We focus on enforcing access control by encrypting the data and managing the encryption keys. We make the realistic assumption that the structure of any organization is a hierarchy of security classes. Data from a certain security class can only be accessed by another security class, if it is higher or at the same level in the hierarchy. Otherwise access is denied. Our solution is based on the Die-Hellman key exchange protocol. We show, that the theoretical worst case performance of our solution is slightly better than that of all other existing solutions. We also show, that our performance in practical cases is linear in the size of the hierarchy, whereas the best results from the literature are quadratic

A Tight Bound for Shortest Augmenting Paths on Trees

The shortest augmenting path technique is one of the fundamental ideas used in maximum matching and maximum flow algorithms. Since being introduced by Edmonds and Karp in 1972, it has been widely applied in many different settings. Surprisingly, despite this extensive usage, it is still not well understood even in the simplest case: online bipartite matching problem on trees. In this problem a bipartite tree $T=(W \uplus B, E)$ is being revealed online, i.e., in each round one vertex from $B$ with its incident edges arrives. It was conjectured by Chaudhuri et. al. [K. Chaudhuri, C. Daskalakis, R. D. Kleinberg, and H. Lin. Online bipartite perfect matching with augmentations. In INFOCOM 2009] that the total length of all shortest augmenting paths found is $O(n \log n)$. In this paper, we prove a tight $O(n \log n)$ upper bound for the total length of shortest augmenting paths for trees improving over $O(n \log^2 n)$ bound [B. Bosek, D. Leniowski, P. Sankowski, and A. Zych. Shortest augmenting paths for online matchings on trees. In WAOA 2015].Comment: 22 pages, 10 figure

Intestinal colic in newborn babies: incidence and methods of proceeding applied by parents

Introduction: Intestinal colic is one of the more frequent complaints that a general practitioner and paediatrician deal with in their work. 10-40% of babies formula fed and 10-20% breast fed are stricken by this complaint. A colic attack appears suddenly and very quickly causes energetic, squeaky cry or even scream. Colic attacks last for a few minutes and appear every 2-3 hours usually in the evenings. Specialist literature provides numerous definitions of intestinal colic. The concept was introduced for the first time to paediatric textbooks over 250 years ago. One of the most accurate definitions describe colic as recurring attacks of intensive cry and anxiety lasting for more than 3 hours a day, 3 days a week within 3 weeks. Care of a baby suffering from an intestinal colic causes numerous problems and anxiety among parents, therefore knowledge of effective methods to combat this complaint is a challenge for contemporary neonatology and paediatrics.The aim of the study is to estimate the incidence of intestinal colic in newborn babies formula and breast fed as well as to assess methods of proceeding applied by parents and analyze their effectiveness.Material and methods: The research involved 100 newborn babies breast fed and 100 formula fed, and their parents. The research method applied in the study was a diagnostic survey conducted by use of a questionnaire method.Results: Among examined newborn babies that were breast fed, 43% have experienced intestinal colic, while among those formula fed 30% have suffered from it. The study involved 44% new born female babies and 56% male babies. 52% of mothers were 30-34 years old, 30% 35-59 years old, and 17% 25-59 years old. When it comes to families, the most numerous was a group in good financial situation (60%). The second numerous group was that in average financial situation (40%). All the respondents claimed that they had the knowledge on intestinal colic and the main source of knowledge was Internet (83.6%). The most frequent methods applied by the parents to combat colic are: carrying the baby (78%), belly massage (72%), and bath (63%).Conclusions: The most frequent methods to combat intestinal colic are behavioural methods and pharmacotherapy that have proved to be equally effective. According to mothers who breast feed their babies, diet was the least effective method to combat the colic

The Power of Dynamic Distance Oracles: Efficient Dynamic Algorithms for the Steiner Tree

In this paper we study the Steiner tree problem over a dynamic set of terminals. We consider the model where we are given an $n$-vertex graph $G=(V,E,w)$ with positive real edge weights, and our goal is to maintain a tree which is a good approximation of the minimum Steiner tree spanning a terminal set $S \subseteq V$, which changes over time. The changes applied to the terminal set are either terminal additions (incremental scenario), terminal removals (decremental scenario), or both (fully dynamic scenario). Our task here is twofold. We want to support updates in sublinear $o(n)$ time, and keep the approximation factor of the algorithm as small as possible. We show that we can maintain a $(6+\varepsilon)$-approximate Steiner tree of a general graph in $\tilde{O}(\sqrt{n} \log D)$ time per terminal addition or removal. Here, $D$ denotes the stretch of the metric induced by $G$. For planar graphs we achieve the same running time and the approximation ratio of $(2+\varepsilon)$. Moreover, we show faster algorithms for incremental and decremental scenarios. Finally, we show that if we allow higher approximation ratio, even more efficient algorithms are possible. In particular we show a polylogarithmic time $(4+\varepsilon)$-approximate algorithm for planar graphs. One of the main building blocks of our algorithms are dynamic distance oracles for vertex-labeled graphs, which are of independent interest. We also improve and use the online algorithms for the Steiner tree problem.Comment: Full version of the paper accepted to STOC'1

Vertex Disjoint Paths for Dispatching in Railways

We study variants of the vertex disjoint paths problem in planar graphs where paths have to be selected from a given set of paths. We study the problem as a decision, maximization, and routing-in-rounds problem. Although all considered variants are NP-hard in planar graphs, restrictions on the location of the terminals, motivated by railway applications, lead to polynomially solvable cases for the decision and maximization versions of the problem, and to a $p$-approximation algorithm for the routing-in-rounds problem, where $p$ is the maximum number of alternative paths for a terminal pair

Paradygmat słowotwórczy jako jednostka badań konfrontatywnych

The present paper addresses the issue of the confrontative analysis of Russian and Polish morphology. Central to the analysis is the morphological paradigm of Russian and Polish adjectives denoting colour. Adopting a confrontative approach is of assistance in determining the rules governing the morphological systems of the languages undergoing analysis in terms of the discrepancies and the analogies that can be drawn between them. The analysis of specific paradigms makes it possible to discern those formants of morphological categories which are characteristic of each of the analysed languages. Within this framework, it is feasible to define the activity of every morphological type and to determine synonymous and homonymic morphological morphemes. The research focusing on typical paradigms facilitates the perception of systematic differences. Moreover, such an approach makes it possible to determine potential derivative groups, i.e. those which are not listed in dictionaries and thus do not constitute a part of a given paradigm

Analiza strukturalno-semantyczna polskich i rosyjskich gniazd słowotwórczych z przymiotnikami wyjściowymi "zielony - zelenyj"

The article addresses the question of how individual meanings forming the semantic structure of adjectives zielony and aeAenbiu are realised in their derivative forms. It has been analysed whether the similarity of the semantic structure of the base words results in sturctural and semantic similarity of the analysed nests and which factors entail differences. The analysis is synchronic and the material comes from dictionaries of contemporary Russian and Polish, including the novel formation and senses that have appeared recently

Dynamic Coloring of Unit Interval Graphs with Limited Recourse Budget

In this paper we study the problem of coloring a unit interval graph which changes dynamically. In our model the unit intervals are added or removed one at the time, and have to be colored immediately, so that no two overlapping intervals share the same color. After each update only a limited number of intervals are allowed to be recolored. The limit on the number of recolorings per update is called the recourse budget. In this paper we show, that if the graph remains k-colorable at all times, the updates consist of insertions only, and the final instance consists of n intervals, then we can achieve an amortized recourse budget of $\u1d4aa({k⁷ log n})$ while maintaining a proper coloring with k colors. This is an exponential improvement over the result in [Bartłomiej Bosek et al., 2020] in terms of both k and n. We complement this result by showing the lower bound of $Ω(n)$ on the amortized recourse budget in the fully dynamic setting. Our incremental algorithm can be efficiently implemented. As an additional application of our techniques we include a new combinatorial result on coloring unit circular arc graphs. Let L be the maximum number of arcs intersecting in one point for some set of unit circular arcs $\u1d49c$. We show that if there is a set $\u1d49c'$ of non-intersecting unit arcs of size $L²-1$ such that $\u1d49c ∪ \u1d49c'$ does not contain L+1 arcs intersecting in one point, then it is possible to color $\u1d49c$ with L colors. This complements the work on circular arc coloring [Belkale and Chandran, 2009; Tucker, 1975; Valencia-Pabon, 2003], which specifies sufficient conditions needed to color $\u1d49c$ with L+1 colors or more

Wpływ przewartościowań semantycznych na budowę gniazd słowotwórczych

"W literaturze językoznawczej niejednokrotnie podkreślano, iż wpływ na strukturę i semantykę gniazda słowotwórczego - kształtowanie się stosunków derywacyjnych między jego leksemami oraz formowanie zasobu leksykalnego - wywiera przynależność słowa wyjściowego do określonej części mowy oraz jego struktura semantyczna. Wyrazy wyjściowe cechujące się bogatą semantyką, dużą liczbą wariantów leksykalno-semantycznych zazwyczaj powołują do życia znacznie więcej pochodnych niż te, które charakteryzują się niewielką liczbą znaczeń lub są słowami jednoznacznymi. Dzieje się tak dlatego, że potencjalnie każde ze znaczeń wyrazu poiisemicznego może stanowić podstawę powstania określonej grupy derywatów (por. np. pochodne, utworzone na podstawie znaczenia przenośnego przymiotnika чёрный ‘отрицательный, плохой’: чёрный - чернить - очернить - очернитель - очернительство; очернять - очерняться). Gniazda, w których centrum znajdująsię jednostki jednoznaczne, są zazwyczaj mniej rozbudowane (por. np. liczebność gniazd z centrum белый i коричневый)." (fragm.