We develop the coalgebraic theory of nominal Kleene algebra, including an alternative language-theoretic semantics, a nominal extension of the Brzozowski derivative, and a bisimulation-based decision procedure for the equational theory.

Recently, a very general description logic (DL) that extends SROIQ (the DL underlying OWL 2 DL) at the same time with nominal schemas and epistemic modal operators has been proposed, which encompasses some of the most prominent monotonic and non-monotonic rule languages, including Datalog under the answer set semantics. A decidable fragment is also presented, but the restricted language does no...

We use an Eulerian hydrodynamic cosmological simulation to model the Lyα forest in a spatially flat, COBE normalized, cold dark matter model with Ω = 0.4, and find that the intergalactic, photoionized gas is predicted to collapse into sheet-like and filamentary structures which give rise to absorption lines having similar characteristics as the observed Lyα forest. A typical filament is ∼ 1hMpc...

When reasoning about inductively defined predicates, such as typing judgements or reduction relations, proofs are often done by a case analysis on the last rule of a derivation. In HOL and other formal frameworks this case analysis involves solving equational constraints on the arguments of the inductively defined predicates. This is well-understood when the arguments consist of variables and i...

Quantification and nominal anaphora is a rich and complex area of research, which has attracked many people; especially since the development of dynamic semantics in the early eigthies. One way to obtain a systematic view on this field, is to focus on the quantificational resources employed to interpret anaphoric relationships. In this article, I will develop such a view as far as first-order q...

The emerging field of Nominal Computation Theory is concerned with the theory of Nominal Sets and its applications to Computer Science. We investigate here the impact of nominal sets on the definition of Cellular Automata and on their computational capabilities, with a special focus on the emergent behavioural properties of this new model and their significance in the context of computationorie...

This thesis studies two major extensions of nominal terms. In particular, we study an extension with λ-abstraction over nominal unknowns and atoms, and an extension with an arguably better theory of freshness and α-equivalence. Nominal terms possess two levels of variable: atoms a represent variable symbols, and unknowns X are ‘real’ variables. As a syntax, they are designed to facilitate metap...

FIROUGHOUT 1989, popular wisdom held that the U.S. monetary authority was faced with a daunting policy task: it should not permit too much money growth and cause prices to rise too rapidly, but it should not allow too little money growth and cause the economy to tip into recession as real output would fall. Sympathy for monetary policymakers, however, is not necessarily widespread among economi...

Nominal terms use a characteristic combination of features: Two levels of variable: atoms a and unknowns X. Freshness conditions a#X and permutations π. An abstraction [a]r with a distinctive α-equivalence based on freshness and permutation. The first statement above is rendered in nominal terms as the equality judgement b#X ` [a]X =α [b](b a) ·X. a and b denote atoms, which represent the ‘x’ a...