My research involves finding bounds of graph theoretic invariants, in particular the independence number of a graph; constructing algorithms for calculating values of these invariants; investigating the structure of independent sets of vertices in graphs; and identifying and programming successful heuristics for automating conjecture-making. of these conjectures have involved the independence n...

Abstract. Colourful and ever-changing: Graffiti can be considered the urban chameleon skin. At Donaukanal (Eng. Danube Channel), Vienna's central waterway one of largest most active graffiti-scapes worldwide, this metaphor applies like hardly anywhere else. Every day a multitude graffiti is destroyed by creation new works. Recently, efforts have been made to mitigate constant loss cultural heri...

The intensity values of terrestrial laser scanning (TLS) can be used to reveal painted black rock art behind graffiti and moss. effect was observed in Gumahon cave Peñablanca, Philippines where previously unnoticed pigment exposed underneath moss, red white graffiti, etched name graffiti. application TLS for this purpose has not, our knowledge, been reported. significance finding is that archae...

Most researchers use Petri nets as a formal notation with mathematically defined semantics. Their graphical part is usually only seen as a notation, that does not carry semantics. Contrary to this tradition, we show in this article that, when created by a human, there is inherent semantics in the positions of places, transitions and arcs. We propose to use the full definition of Petri nets: whe...