Improved Bounds for rr-Identifying Codes of the Hex Grid

For any positive integer $r$, an $r$-identifying code on a graph $G$ is a set $C\subset V(G)$ such that for every vertex in $V(G)$, the intersection of the radius-$r$ closed neighborhood with $C$ is nonempty and pairwise distinct. For a finite graph, the density of a code is $|C|/|V(G)|$, which naturally extends to a definition of density in certain infinite graphs which are locally finite. We find a code of density less than $5/(6r)$, which is sparser than the prior best construction which has density approximately $8/(9r)$.Comment: 12p

On two variations of identifying codes

Identifying codes have been introduced in 1998 to model fault-detection in multiprocessor systems. In this paper, we introduce two variations of identifying codes: weak codes and light codes. They correspond to fault-detection by successive rounds. We give exact bounds for those two definitions for the family of cycles

Identifying codes and locating–dominating sets on paths and cycles

AbstractLet G=(V,E) be a graph and let r≥1 be an integer. For a set D⊆V, define Nr[x]={y∈V:d(x,y)≤r} and Dr(x)=Nr[x]∩D, where d(x,y) denotes the number of edges in any shortest path between x and y. D is known as an r-identifying code (r-locating-dominating set, respectively), if for all vertices x∈V (x∈V∖D, respectively), Dr(x) are all nonempty and different. Roberts and Roberts [D.L. Roberts, F.S. Roberts, Locating sensors in paths and cycles: the case of 2-identifying codes, European Journal of Combinatorics 29 (2008) 72–82] provided complete results for the paths and cycles when r=2. In this paper, we provide results for a remaining open case in cycles and complete results in paths for r-identifying codes; we also give complete results for 2-locating-dominating sets in cycles, which completes the results of Bertrand et al. [N. Bertrand, I. Charon, O. Hudry, A. Lobstein, Identifying and locating–dominating codes on chains and cycles, European Journal of Combinatorics 25 (2004) 969–987]

Identifying and locating-dominating codes on chains and cycles

AbstractConsider a connected undirected graph G=(V,E), a subset of vertices C⊆V, and an integer r≥1; for any vertex v∈V, let Br(v) denote the ball of radius r centered at v, i.e., the set of all vertices within distance r from v. If for all vertices v∈V (respectively, v∈V ⧹C), the sets Br(v)∩C are all nonempty and different, then we call C an r-identifying code (respectively, an r-locating-dominating code). We study the smallest cardinalities or densities of these codes in chains (finite or infinite) and cycles

Lokaali identifiointi graafeissa

Tässä tutkielmassa esitellään kaksi uutta peittokoodien luokkaa - lokaalisti identifioivat koodit ja lokaalisti paikallistavat-dominoivat koodit - ja todistetaan näihin liityviä tuloksia eri graafeissa. Tuloksia verrataan vastaaviin tunnettuihin tuloksiin koskien identifioivia ja paikallistavia-dominoivia koodeja. Myös vertailua peittokoodeihin tehdään. Tutkielma alkaa lyhyellä johdannolla aiheeseen, jonka jälkeen esitellään suurin osa tarvittavista käsitteistä ja määritelmistä toisessa luvussa. Kolmannessa luvussa tutkitaan lyhyesti lokaalisti identifioivia koodeja poluissa ja sykleissä sekä erityisesti niiden suhdetta identifioiviin koodeihin samaisissa graafeissa. Luvussa neljä tarkastellaan identifiointia binäärisissä hyperkuutioissa ja todistetaan tuloksia lokaalisti 1-identifioiville koodeille näissä graafeissa. Viimeisessä luvussa siirrytään joihinkin äärrettömiin hiloihin, joissa tutkitaan lokaalisti 1-identifioivia ja lokaalisti 1-paikallistavia-dominoivia koodeja

On Vertex Identifying Codes For Infinite Lattices

PhD Thesis--A compilation of the papers: "Lower Bounds for Identifying Codes in Some Infinite Grids", "Improved Bounds for r-identifying Codes of the Hex Grid", and "Vertex Identifying Codes for the n-dimensional Lattics" along with some other resultsComment: 91p