Talk:Tomaž Pisanski

Letter ž not in Latin 1

ISO-8859-1 (ISO Latin 1) character set does not contain the necessary "z" with a caron. Is there some standard for using them on Wikipedia? I can imagine people linking to [[Tomaz Pisanski]], but can't figure how to link to [[Tomaz<caron> Pisanski]] and can't imagine what [[Tomaž Pisanski]] is <G>. -- Someone else 05:33 May 6, 2003 (UTC)

ž is &#382;. I think I mistyped it when I was trying to move the article - hence [[Tomaž Pisanski]] - but maybe it would have done that anyway. And now I can't even put it back where it was. Drat.

--Paul A 05:53 May 6, 2003 (UTC)

You may need a developer to fix it (you might want to drop a note to User talk:Brion VIBBER). I seem to recall there was some reason that diacriticals are not preferred in article titles... this may be that reason <G> -- Someone else 06:00 May 6, 2003 (UTC)

I moved it back to Tomaz Pisanski. No developer involvement required, just a simple deletion to make way. Call me a cultural imperialist, but I prefer URLs I can type without looking up a character map. -- Tim Starling 06:08 May 6, 2003 (UTC)

Sorry! I thought it was part of Latin-1. Stan 12:44 May 6, 2003 (UTC)

Title

Text moved from the Village pump

In a well-meaning attempt to improve things, I've done something terrible to the title of the Tomaz Pisanski article. Help!! -- Paul A 05:32 May 6, 2003 (UTC)

Wow, cool. Reading it makes me feel like I am in a surreal dyslexia. Kingturtle 05:37 May 6, 2003 (UTC)

I moved it back to Tomaz Pisanski. Further discussion on Talk:Tomaz Pisanski -- Tim Starling 06:04 May 6, 2003 (UTC)

End of moved text

Why does this biography exist?

Hi all, I have nominated this article for deletion on grounds of non-notable biography. If you disagree, please see the talk page for the vfd. The best counterargument would be writing a good article on a clearly interesting/important theorem proven by Pisanski, or at least naming such a theorem. E.g. I just cated into this category the biography of Bill Tutte, about whom there is no argument over notability, but if there were, I could point to existing articles on some of his theorems. BTW, someone needs to write the most important one, on Tutte polynomial. I could write it, but lack time right now.---CH (talk) 23:32, 21 August 2005 (UTC)

Well, I didn't follow the procedure correctly the first time and I'm trying to fix it up now.---CH (talk) 18:56, 22 August 2005 (UTC)

Here are some of the requested contributions:

• In 1980 Pisanski calculated the genus of the Cartesian product of any pair of connected, bipartite, d-valent graphs.

• In 1982 Vladimir Batagelj and Pisanski proved that the Cartesian product of a tree and a cycle is Hamiltonian if and only if no degree of the tree exceeds the length of the cycle.

• A cycle permutation graph is a trivalent graph which consists of two disjoint copies $C_n$ and $C_n'$ of a cycle of length $n$ and in which each vertex of $C_n$ is adjacent with exactly one vertex of $C_n'$. In 1982 Pisanski and John Shawe-Taylor proved that there are cycle permutation graphs with arbitrarily large girth.

• Pisanski and Joze Vrabec were the first to introduce the concept of a graph bundle. They consider graph bundles in a purely combinatorial fashion without any reference to topology. Just as the topological notion of a fibre bundle is a generalization both of a Cartesian product and of a covering space, so is a graph bundle a generalization both of a Cartesian product of two graphs and of a covering graph. A graph bundle can be intuitively described as the 1-skeleton of a fibre bundle where both the base and the fibre are graphs. In 1983 Pisanski, John Shawe-Taylor and Joze Vrabec studied edge-colorings of graph bundles.

• The Wiener index (the Wiener number) of a graph G is equal to the sum of distances between all pairs of vertices of G. It has been found that the Wiener index of a molecular graph correlates with certain physical and chemical properties of the corresponding molecule. An algorithm that calculates the Wiener index of a tree in linear time was published by Bojan Mohar and Pisanski in 1988.

• In the eighties, Torrence Parsons and Pisanski have studied the notion of vector representation of graphs. They considered various representations of a graph by vectors. They posed the problem of finding the least dimension $d$ for which certain representations exist. They applied their methods to such problems as constructing universal graphs, and representing a graph as a set intersection graph.

• In a series of papers Pisanski and co-authors have studied embeddings of Cayley graphs into orientable or nonorientable surfaces. For many abelian groups, many Hamiltonian groups, and some metacylic groups they calculated the the orientable genus and nonorientable genus is calculated.

• In 1994 John Shawe-Taylor and Pisanski proved that determining whether two 2-complexes are homeomorphic is as hard as showing that two graphs are isomorphic, in terms of computational complexity.

• A symmetric $n \sb k$-configuration is an ordered triple ${\scr C}=(P, {\scr B}, I)$ of mutually disjoint sets $P$, $\scr B $ and $I$ (called points, blocks and flags) with $I \subseteq P \times {\scr B}$ and (with a point $p$ and block $B$ called incident if $(p,B) \in I$) such that $|P|=|{\scr B}|=n$ and each point [block] is incident with $k$ blocks [points]. To a configuration one can associate their Levi graph, the bipartite graph on points and blocks. Let ${\rm Aut} ({\scr C})$ denote the group of incidence-preserving permutations of $P \cup {\scr B}$ and let ${\rm Aut}\sb 0 ({\scr C})$ denote the subgroup of ${\rm Aut} ({\scr C})$ which preserves the set $P$. A configuration is called weakly flag-transitive if ${\rm Aut} ({\scr C})$ acts transitively but ${\rm Aut}\sb 0 ({\scr C})$ acts intransitively on the set of flags. A graph is called $1 \over 2$-arc-transitive if its group of automorphisms is transitive on vertices and edges but not on 1-arcs. In 1999 Dragan Marusic and Pisanski proved that weakly flag-transitive symmetric $n \sb k$-configurations are in one-to-one correspondence with bipartite $1 \over 2$-arc transitive graphs of girth at least 6. They then applied the result to construct several families of weakly flag-transitive symmetric $n \sb k$-configurations for various values of $n$ and $k$.

• In 2001 Pisanski and Thomas W. Tucker have shown that the spherical growth function of repeated truncations of maps tends to a universal function 1+3x+4x^2+6x^3+6x^4+6x^5+8x^6+12x^7+10x^8+6x^9+ ... which is independent of the original map as well as of the initial vertex of the truncated map, compare [[1]]

• A snark is a non-trivial cubic graph admitting no Tait coloring. In 2004 Pisanski and co-authors examined the structure of the two known snarks on 18 vertices, the Blanusa graph and the Blanusa double. By showing that one is of genus 1, the other of genus 2, they obtain maps on the torus and double torus which are not 4-colorable. The Blanusa graphs also serve as a counterexample to the conjecture that the orientable genus of a dot product of n Petersen graphs is n-1.

• A g-cage is a cubic graph of girth $g$ with as few vertices as possible. Cages have been classified exactly up to girth 12, while for larger girth, researchers are finding ever smaller candidate graphs. For even girth, the known cages are bipartite and hence can be viewed as point/line incidence geometries and indeed some famous geometries such as the Fano plane and generalized hexagon of order two arise. Motivated by this connection, Pisanski and his co-authors explore the three known 10-cages viewing them both as graphs and as geometries. They give drawings for the cages, give their LCF notation, give presentations for them as voltage graphs and give the orders of their automorphism groups. Viewed as geometries (where each point lies on 3 lines and each line has 3 points) they show that the cages can be realized in the Euclidean plane with straight lines and give the resulting attractive drawings. The paper published in 2004 concludes with the conjecture that all cages of even girth are bipartite. 193.2.67.50 12:04, 27 August 2005 (UTC)

Expert, please add requested explanation

The VfD has ended--- whew! Thanks to all for your thoughts; this was my first VfD (probably not my last) and it has been a learning experience for me. I just mildly improved the paragraph breaks in the article and set things up for an expert editor to tell us all something about P's contributations.

193.2.67.50, can you choose the most important of one or two of the contributions you listed, write a description explaining the contribution and its importance in the subject in non-expert level language suitable for undergraduate math students, and add this essential information after the mention of White-Pisanski method? Then delete the "{expert}" template at the top. TIA---CH (talk) 17:56, 29 August 2005 (UTC)

VFD debate link

This article has been kept following this VFD debate. Sjakkalle (Check!) 11:26, 29 August 2005 (UTC)

And it wound up being much improved! What was lacking before? Information about Pisanski's mathematical work, which made him appear non-notable even to at least one user with a mathematical background. Lesson? When adding a biostub for a mathematician, start with some cogent description of mathematical work, and add a citation for verfiability. Then later edits can add routine biographical information.

That's how I see it, anyway.---CH (talk) 21:57, 7 October 2005 (UTC)

Requested move

Correct name. -- Naive cynic 15:34, 29 August 2005 (UTC)

Add *Support or *Oppose followed by an optional one sentence explanation and sign your vote with ~~~~.

Discussion

Add any additional comments.

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