THE ELECTRONIC JOURNAL OF COMBINATORICS (ed. March 2001), DS #5. |

Footnotes

^{1} By *C*(*n*,*k*) we denote the binomial
coefficient *n*!/(*k*!(*n-k*)!).

^{2} Two figures in the plane are *congruent* if one
can be transformed into the other by rotations and translations in
the plane.

^{3} A graph is *three-connected* if the removal of
any two vertices (and the adjacent edges) leaves a connected graph.

^{4} The *prism* of a graph *G* is formed by taking
two copies of *G* and adding a perfect matching whose edges join
corresponding copies of vertices.

^{5} A *planar graph* is one that can be embedded in the plane
without crossing edges. A *plane* graph is a planar graph that has
been embedded in the plane.

^{6} The *square* of a graph *G*,
denoted *G*^{2},
is the graph obtained from *G* by adding edges between vertices if
they are at distance 2 in *G*.
All of the original edges of *G* are present in
*G*^{2}.

^{7} A *link* is a finite collection of
non-intersecting knots.
A *Brunnian link* is a link which is non-trivial,
yet every proper sub-collection is trivial.
A *trivial link* is one that can be projected to a collection of
non-intersecting circles in the plane.

^{8} A *bipartite* graph is one in which the vertices can be
partitioned into two sets *A* and *B* where every edge is
incident with a vertex from *A* and a vertex from *B*.
The *n*-cube is bipartite, and thus so is the Venn graph.

^{9} A *binary De Bruijn cycle* of order *n* is a
circular binary sequence of length 2^{n} with the property
that all length *n* subsequences are distinct.

THE ELECTRONIC JOURNAL OF COMBINATORICS (ed. March 2001), DS #5. |