We show how to accept a context-free language nondeterministically in O( n log n) time on a two-queue machine.

We discuss the notion of privileged word, recently introduced by Peltomäki. A word w is privileged if it is of length ≤ 1, or has a privileged border that occurs exactly twice in w. We prove the following results: (1) if wk is privileged for some k ≥ 1, then wj is privileged for all j ≥ 0; (2) the language of privileged words is neither regular nor context-free; (3) there is a linear-time algor...

Given a positive integer n and a finite alphabet Σ, a word w over Σ is said to guarantee minimum image if, for every homomorphism φ from the free monoid Σ∗ over Σ into the monoid of all transformations of an n-element set, the range of the transformation wφ has the minimum cardinality among the ranges of all transformations of the form vφ where v runs over Σ∗ . Although the existence of words g...

The principle known as 'free indexation' plays an important role in the determination of the refer-ential properties of noun phrases in the principle-and-parameters language framework. First, by investigating the combinatorics of free indexation, we show that the problem of enumerating all possible indexings requires exponential time. Secondly, we exhibit a provably optimal free indexation algo...

Given a positive integer n and a finite alphabet Σ, a word w over Σ is said to guarantee minimum image if, for every homomorphism φ from the free monoid Σ∗ over Σ into the monoid of all transformations of an n-element set, the range of the transformation wφ has the minimum cardinality among the ranges of all transformations of the form vφ where v runs over Σ∗ . Although the existence of words g...

We present a new proof that O2 is a multiple context-free language. It contrasts with a recent proof by Salvati (2015) in its avoidance of concepts that seem specific to two-dimensional geometry, such as the complex exponential function. Our simple proof creates realistic prospects of widening the results to higher dimensions. This finding is of central importance to the relation between extrem...

In this paper we study the quasi-static problem for a viscoelastic fluid by means of the concept of minimal state. This implies the use of a different free energy defined in a wider space of data. The existence and uniqueness is proved in this new space and the asymptotic decay for the problem with non vanishing supplies is obtained for a large class of memory kernels, including those presentin...

It is known that the number of overlap-free binary words of length n grows polynomially, while the number of cubefree binary words grows exponentially. We show that the dividing line between polynomial and exponential growth is 73 . More precisely, there are only polynomially many binary words of length n that avoid 7 3 -powers, but there are exponentially many binary words of length n that avo...

Type Ia supernovae (SN Ia) have provided the first evidence for an accelerating universe and for the existence of an unknown “dark energy” driving this expansion. The 5-year Supernova Legacy Survey (SNLS) will deliver ∼700 type Ia supernovae and as many type II supernovae with wellsampled light curves in 4 filters g′, r′, i′ and z′. The current status of the project will be presented, along wit...