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#### The number of order–preserving maps of fences and crowns

(Springer, 1991-06)

We perform an exact enumeration of the order-preserving maps of fences (zig-zags) and crowns (cycles). From this we derive asymptotic results.

#### A Characterization of Fractionally Well-Covered Graphs

(Ars Combinatoria, 1991)

A graph is called well-covered if every maximal independent set has the same size. One generalization of independent sets in graphs is that of a fractional cover -- attach nonnegative weights to the vertices and require ...

#### A Note on Antichains of Words

(The Electronic Journal of Combinatorics, 1995-10-14)

We can compress the word 'banana' as xyyz, where x= 'b', y= 'an',z= 'a'. We say that 'banana' encounters yy. Thus a 'coded' version of yy shows up in 'banana'. The relation 'u encounters w' is transitive, and thus generates ...

#### Extremal Infinite Overlap-Free Binary Words

(The Electronic Journal of Combinatorics, 1998-05-03)

Let t be the infinite fixed point, starting with 1, of the morphism μ:0→01, 1→10. An infinite word over {0,1} is said to be overlap-free if it contains no factor of the form axaxa, where a∈{0,1} and x∈{0,1}∗. We prove that ...

#### Words without Near-Repetitions

(Canadian Mathematical Society, 1992-06-01)

We find an infinite word w on four symbols with the following property: Two occurrences of any block in w must be separated by more than the length of the block. That is, in any subword of w of the form xyx, the length of ...