for a graph $g$ let $gamma (g)$ be its domination number. we define a graph g to be (i) a hypo-efficient domination graph (or a hypo-$mathcal{ed}$ graph) if $g$ has no efficient dominating set (eds) but every graph formed by removing a single vertex from $g$ has at least one eds, and (ii) a hypo-unique domination graph (a hypo-$mathcal{ud}$ graph) if $g$ has at least two minimum dominating sets...

For a graph $G$ let $gamma (G)$ be its domination number. We define a graph G to be (i) a hypo-efficient domination graph (or a hypo-$mathcal{ED}$ graph) if $G$ has no efficient dominating set (EDS) but every graph formed by removing a single vertex from $G$ has at least one EDS, and (ii) a hypo-unique domination graph (a hypo-$mathcal{UD}$ graph) if $G$ has at least two minimum dominating sets...

Discodon tricolor (Guérin-Méneville, 1832) was thought to be a common species widely distributed in the Atlantic Forests of Brazil, yet showing morphological and chromatic variations. After examination large number specimens from different regions Forest biome, we found that actually represents complex many similar sometimes sympatric species. Thirteen this are recognised as valid: tricolor, D....

Given a graph G and a positive integer r, let sr(G)=P(G; r)=r!. Thus (G)=r and sr(G)=1 i G is uniquely r-colourable. It is known that if G is uniquely 3-colourable, then e(G)¿2v(G)−3. In this paper, we show that if G is a 3-colourable connected graph with e(G)=2v(G)−k where k¿4, then s3(G)¿2k−3; and if, further, G is 2-connected and s3(G)=2k−3, then t(G)6v(G)−k where t(G) denotes the number of ...

It has been suggested that there are two types of chromatic motion mechanisms: signed chromatic motion, in which correspondence across successive frames is based on chromatic content of image regions, and unsigned chromatic motion based on movement of chromatically-defined borders. We investigate whether signed and unsigned red-green chromatic motion are mediated by a genuinely chromatic mechan...

Few studies have investigated the possible role of higher-level cognitive mechanisms in color constancy. Following up on previous work with successive color constancy [J. Exper. Psychol. Learn. Mem. Cogn. 37, 1014 (2011)], the current study examined the relation between simultaneous color constancy and working memory-the ability to maintain a desired representation while suppressing irrelevant ...

This study provides evidence for the existence of a low-level chromatic motion mechanism and further elucidates the conditions under which its operation becomes measurable in an experimental stimulus. Observers discriminated the direction of motion of amplitude modulated (AM) gratings that were defined by luminance or chromatic variation and masked with spatiotemporally broadband luminance or c...