In this work, two different classes of polyaromatic hydrocarbon (PAH) systems have been investigated in order to characterize the amount of polyradical character and to localize the specific regions of chemical reactivity: (a) the non-Kekulé triangular structures phenalenyl, triangulene and a π-extended triangulene system with high-spin ground state and (b) PAHs based on zethrenes, p-quinodimet...

Some physical and chemical properties of the cancerostat cyclophosphamide (generic name: ENDOXAN) and its basic constituents H3PO4 and nor-N-mustard have been calculated with the help of a modified CNDO/S-method. The spectroscopic data of the H3PO4, which is the starting-point for a corresponding calculation of cyclophosphamide, has been studied by taking account of the 3 d electron of the phos...

Consider the following forest-fire model where trees are located on sites of Z. A site can be vacant or be occupied by a tree. Each vacant site becomes occupied at rate 1, independently of the other sites. Each site is hit by lightning with rate λ, which burns down the occupied cluster of that site instantaneously. As λ ↓ 0 this process is believed to display self-organised critical behaviour. ...

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The Zarankiewicz number z(b; s) is the maximum size of a subgraph of Kb,b which does not contain Ks,s as a subgraph. The two-color bipartite Ramsey number b(s, t) is the smallest integer b such that any coloring of the edges of Kb,b with two colors contains a Ks,s in the rst color or a Kt,t in the second color.In this work, we design and exploit a computational method for bounding and computing...

it is well known fact that binary relations are generalized mathematical functions. contrary to functions from domain to range, binary relations may assign to each element of domain two or more elements of range. some basic operations on functions such as the inverse and composition are applicable to binary relations as well. depending on the domain or range or both are fuzzy value fuzzy set, i...