Polynomial vector fields which admit a prescribed Darboux integrating factor are quite well-understood when the geometry of the underlying curve is nondegenerate. In the general setting morphisms of the affine plane may remove degeneracies of the curve, and thus allow more structural insight. In the present paper we establish some properties of integrating factors subjected to morphisms, and we...

We extend the ordinary concept of theory morphism in institutions to extra theory morphisms. Extra theory morphism map theories belonging to different institutions across institution morphisms. We investigate the basic mathematical properties of extra theory morphisms supporting the semantics of logical multiparadigm languages, especially structuring specifications (module systems) á la OBJ-Cle...

In the design of concurrent and distributed systems, modularity and refinement are basic conceptual tools. We propose a notion of refinement/abstraction of local states for a basic class of Petri Nets, associated with a new kind of morphisms. The morphisms, from a refined system to an abstract one, associate suitable subnets to abstract local states. The main results concern behavioural propert...

We show that every λm-injectivity class (i.e., the class of all the objects injective with respect to some class of λ-presentable morphisms) is a weakly reflective subcategory determined by a functorial weak factorization system cofibrantly generated by a class of λ-presentable morphisms. This was known for small-injectivity classes, and referred to as the “small object argument”. An analogous ...

This article addresses the existence of Q-rational periodic points for morphisms of projective space. In particular, we construct an infinitely family of morphisms on P where each component is a degree 2 homogeneous form in N+1 variables which has a Q-periodic point of primitive period (N+1)(N+2) 2 + ̈ N−1 2 ̋ . This result is then used to show that for N large enough there exists morphisms of P ...

Morphisms are homomorphisms under the concatenation operation of the set of words over a finite set. Changing the elements of the finite set does not essentially change the morphism. We propose a way to select a unique representing member out of all these morphisms. This has applications to the classification of the shift dynamical systems generated by morphisms. In a similar way, we propose th...

It is well-known that any morphism between two p-compact groups will lift, nonuniquely, to an admissible morphism between the maximal tori. We identify here a class of pcompact group morphisms, the p-toric morphisms, which can be perceived as generalized rational isomorphisms, enjoying the stronger property of lifting uniquely to a morphism between the maximal torus normalizers. We investigate ...

In this thesis we investigate the existence of complex-valued harmonic morphisms on Lie groups and homogeneous Hadamard manifolds. The Lie groups that we are interested in have a particular decomposition of their Lie algebra. This decomposition allows us to define harmonic morphisms to R, n ≥ 2. Any homogeneous Hadamard manifold is isometric to a solvable Lie group S with a left-invariant metri...