Solving Two Conjectures regarding Codes for Location in Circulant Graphs

Identifying and locating-dominating codes have been widely studied in circulant graphs of type $C_n(1,2, \ldots, r)$, which can also be viewed as power graphs of cycles. Recently, Ghebleh and Niepel (2013) considered identification and location-domination in the circulant graphs $C_n(1,3)$. They showed that the smallest cardinality of a locating-dominating code in $C_n(1,3)$ is at least $\lceil n/3 \rceil$ and at most $\lceil n/3 \rceil + 1$ for all $n \geq 9$. Moreover, they proved that the lower bound is strict when $n \equiv 0, 1, 4 \pmod{6}$ and conjectured that the lower bound can be increased by one for other $n$. In this paper, we prove their conjecture. Similarly, they showed that the smallest cardinality of an identifying code in $C_n(1,3)$ is at least $\lceil 4n/11 \rceil$ and at most $\lceil 4n/11 \rceil + 1$ for all $n \geq 11$. Furthermore, they proved that the lower bound is attained for most of the lengths $n$ and conjectured that in the rest of the cases the lower bound can improved by one. This conjecture is also proved in the paper. The proofs of the conjectures are based on a novel approach which, instead of making use of the local properties of the graphs as is usual to identification and location-domination, also manages to take advantage of the global properties of the codes and the underlying graphs

Optimal locating-total dominating sets in strips of height 3

A set C of vertices in a graph G = (V,E) is total dominating in G if all vertices of V are adjacent to a vertex of C. Furthermore, if a total dominating set C in G has the additional property that for any distinct vertices u, &epsilon; &isin; V \ C the subsets formed by the vertices of C respectively adjacent to u and v are different, then we say that C is a locating-total dominating set in G. Previously, locating-total dominating sets in strips have been studied by Henning and Jafari Rad (2012). In particular, they have determined the sizes of the smallest locating-total dominating sets in the finite strips of height 2 for all lengths. Moreover, they state as open question the analogous problem for the strips of height 3. In this paper, we answer the proposed question by determining the smallest sizes of locating-total dominating sets in the finite strips of height 3 as well as the smallest density in the infinite strip of height 3. Optimal locating-total dominating sets in strips of height 3. Available from: https://www.researchgate.net/publication/273517759_Optimal_locating-total_dominating_sets_in_strips_of_height_3 [accessed Jan 28, 2016].</p

Tolerant location detection in sensor networks

Location detection in sensor networks can be handled with so called identifying codes. For an identifying code to work properly, it is required that no sensors are malfunctioning. Previously, malfunctioning sensors have been typically coped with robust identifying codes. However, they are rather large and, hence, imply high signal interference and energy consumption. To overcome these issues, collections of disjoint identifying codes have been proposed for coping with malfunctioning sensors. However, these collections have some problems regarding detection of malfunctioning sensors and, moreover, it seems unnecessary to restrict oneself to disjoint codes. In this paper, we discuss a certain type of identifying codes, for which the detection of malfunctioning sensors is easy, and based on these codes we design a collection of codes tolerant against malfunctions. We present some results on general graphs as well as optimal constructions in rook's graphs and binary Hamming spaces. (C) 2019 Elsevier Inc. All rights reserved

On the Metric Dimensions for Sets of Vertices

Resolving sets were originally designed to locate vertices of a graph one at a time. For the purpose of locating multiple vertices of the graph simultaneously, $\{\ell\}$-resolving sets were recently introduced. In this paper, we present new results regarding the $\{\ell\}$-resolving sets of a graph. In addition to proving general results, we consider $\{2\}$-resolving sets in rook's graphs and connect them to block designs. We also introduce the concept of $\ell$-solid-resolving sets, which is a natural generalisation of solid-resolving sets. We prove some general bounds and characterisations for $\ell$-solid-resolving sets and show how $\ell$-solid- and $\{\ell\}$-resolving sets are connected to each other. In the last part of the paper, we focus on the infinite graph family of flower snarks. We consider the $\ell$-solid- and $\{\ell\}$-metric dimensions of flower snarks. In two proofs regarding flower snarks, we use a new computer-aided reduction-like approach.Comment: 21 pages, 5 figure

Private membership test protocol with low communication complexity

Ramezanian S, Meskanen T, Naderpour M, Junnila V, Niemi V. Private membership test protocol with low communication complexity. Digital Communications and Networks. 2019 May 13.We introduce a practical method to perform private membership tests. In this method, clients are able to test whether an item is in a set controlled by the server without revealing their query item to the server. After executing the queries, the content of the server's set remains secret. One use case for a private membership test is to check whether a file contains any malware by checking its signature against a database of malware samples in a privacy-preserving way. We apply the Bloom filter and the Cuckoo filter in the membership test procedure. In order to achieve privacy properties, we present a novel protocol based on some homomorphic encryption schemes. In our protocol, we rearrange the data in the set into N-dimensional hypercubes. We have implemented our method in a realistic scenario where a client of an anti-malware company wants to privately check whether a hash value of a given file is in the malware database of the company. The evaluation shows that our method is feasible for real-world applications. We also have tested the performance of our protocol for databases of different sizes and data structures with different dimensions: 2-dimensional, 3-dimensional, and 4-dimensional hypercubes. We present formulas to estimate the cost of computation and communication in our protocol.Peer reviewe

The solid-metric dimension

Resolving sets are designed to locate an object in a network by measuring the distances to the object. However, if there are more than one object present in the network, this can lead to wrong conclusions. To overcome this problem, we introduce the concept of solid-resolving sets. In this paper, we study the structure and constructions of solid-resolving sets. In particular, we classify the forced vertices with respect to a solid-resolving set. We also give bounds on the solid-metric dimension utilizing concepts like the Dilworth number, the boundary of a graph, and locating-dominating sets. It is also shown that deciding whether there exists a solid-resolving set with a certain number of elements is an NP-complete problem.</p

On regular and new types of codes for location-domination

Identifying codes and locating-dominating codes have been designed for locating irregularities in sensor networks. In both cases, we can locate only one irregularity and cannot even detect multiple ones. To overcome this issue, self-identifying codes have been introduced which can locate one irregularity and detect multiple ones. In this paper, we define two new classes of locating-dominating codes which have similar properties. These new locating-dominating codes as well as the regular ones are then more closely studied in the rook’s graphs and binary Hamming spaces.In the rook’s graphs, we present optimal codes, i.e., codes with the smallest possible cardinalities, for regular location-domination as well as for the two new classes. In the binary Hamming spaces, we present lower bounds and constructions for the new classes of codes; in some cases, the constructions are optimal. Moreover, one of the obtained lower bounds improves the bound of Honkala et al. (2004) on codes for locating multiple irregularities.Besides studying the new classes of codes, we also present record-breaking constructions for regular locating-dominating codes. In particular, we present a locating-dominating code in the binary Hamming space of length 11 with 320 vertices improving the earlier bound of 352; the best known lower bound for such code is 309 by Honkala et al. (2004).</p