#### Filter Results:

- Full text PDF available (23)

#### Publication Year

1995

2017

- This year (1)
- Last 5 years (8)
- Last 10 years (16)

#### Publication Type

#### Co-author

#### Journals and Conferences

#### Key Phrases

Learn More

- Michael H. Albert, Steve Linton, Nikola Ruskuc
- Electr. J. Comb.
- 2005

We introduce the insertion encoding, an encoding of finite permutations. Classes of permutations whose insertion encodings form a regular language are characterized. Some necessary conditions are provided for a class of permutations to have insertion encodings that form a context free language. Applications of the insertion encoding to the evaluation of… (More)

- Mike D. Atkinson, Maximillian M. Murphy, Nikola Ruskuc
- Order
- 2002

It is known that the \pattern containment" order on permutations is not a partial well-order. Nevertheless, many naturally de ned subsets of permutations are partially well-ordered, in which case they have a strong nite basis property. Several classes are proved to be partially well-ordered under pattern containment. Conversely, a number of new antichains… (More)

- Mike D. Atkinson, Maximillian M. Murphy, Nikola Ruskuc
- Theor. Comput. Sci.
- 2002

- Robert Brignall, Nikola Ruskuc, Vincent Vatter
- Theor. Comput. Sci.
- 2008

Simple permutations are the building blocks of permutation classes. As such, classes with only finitely many simple permutations, e.g., the class of 132-avoiding permutations, have nice properties. To name three: these classes have algebraic generating functions (as established by Albert and Atkinson [1]; see Brignall, Huczynska, and Vatter [9] for… (More)

- Michael H. Albert, Mike D. Atkinson, Nikola Ruskuc
- Theor. Comput. Sci.
- 2003

Machines whose main purpose is to permute and sort data are studied. The sets of permutations that can arise are analysed by means of finite automata and avoided pattern techniques. Conditions are given for these sets to be enumerated by rational generating functions. As a consequence we give the first non-trivial examples of pattern closed sets of… (More)

- Colin M. Campbell, Edmund F. Robertson, Nikola Ruskuc, Richard M. Thomas
- Theor. Comput. Sci.
- 2001

2-We have a group G or a semigroup S with a set of (semigroup) generators A. We have a natural mapping ! : A* " G. Various notions of classes of groups and semigroups give rise to (the possibility of) effective computation. In the cases we will consider, we have L # A + = A*-{$} such that L is regular and L! = G.

- Mike D. Atkinson, Maximillian M. Murphy, Nikola Ruskuc
- Electr. J. Comb.
- 2005

Pattern avoidance classes of permutations that cannot be expressed as unions of proper subclasses can be described as the set of subpermutations of a single bijection. In the case that this bijection is a permutation of the natural numbers a structure theorem is given. The structure theorem shows that the class is almost closed under direct sums or has a… (More)

- Friedrich Otto, Nikola Ruskuc
- Journal of Automata, Languages and Combinatorics
- 2001

- Luís Descalço, Nikola Ruskuc
- IJAC
- 2005

In this paper we give a description of all subsemigroups of the bicyclic monoid B. We show that there are essentially five different types of subsemigroups. One of them is the degenerate case, and the remaining four split in two groups of two, linked by the obvious anti-isomorphism of B. Each subsemigroup is characterized by a certain collection of… (More)

- Steve Linton, Götz Pfeiffer, Edmund F. Robertson, Nikola Ruskuc
- J. Symb. Comput.
- 2002

This paper describes algorithms for computing the structure of finite transformation semigroups. The algorithms depend crucially on a new data structure for an R-class in terms of a group and an action. They provide for local computations, concerning a single R-class, without computing the whole semigroup, as well as for computing the global structure of… (More)