In what sense can instruments and bodies be said to form spaces?

My recent work is an exploration of the physical and conceptual mechanisms that interface people with instruments. Central to this investigation is a conception of the performer/instrument assemblage as a symbiosis of two parallel and interdependent systems: one – the performer – moves through space established by the other – the instrument. Each system possesses its own intrinsic properties and characteristics; each possesses capacities to affect and be affected by one another. The music emanates from this contiguous interaction. Instrument surface is understood as a compositional resource itself, a topological façade, defined by ordinal distances, that guides gestures along its contours. Within these fluctuating constellations of spatial coordinates, I consider all the relevant ways a body can move, and establish some general combinatory rules that inform the convergence of forces within the body. The traditional subjects of compositional contemplation such as form, duration, dynamic, etc. are not attributing features to the work per se but emerge as results from spatiotemporal relations of (bodily) movement’s correspondence with (instrumental) surface and mechanism. This liberation of movement is understood as a liberation of timbre, and the inherent indeterminacy of this relationship is embraced. As such, I would hypothesize that sound is, to an extent, freed from the subtractive tendencies of perception that might otherwise subvert it into generalized typological categories. Once liberated from the imagination, sound can bypass the brain and directly engage the nervous system

Topological relationships between a circular spatially extended point and a line : spatial relations and their conceptual neighborhoods

This paper presents the topological spatial relations that can exist in the geographical space between a Circular Spatially Extended Point and a Line and describes the use of those spatial relations in the identification of the conceptual neighbourhood graphs that state the transitions occurring among relations. The conceptual neighbourhood graphs were identified using the snapshot model and the smooth-transition model. In the snapshot model, the identification of neighbourhood relations is achieved looking at the topological distance existing between pairs of spatial relations. In the smooth-transition model, conceptual neighbours are identified analysing the topological deformations that may change a topological spatial relation. The graphs obtained were analysed as an alternative to map matching techniques in the prediction of the future positions of a mobile user in a road network.(undefined

On Locality in Quantum General Relativity and Quantum Gravity

The physical concept of locality is first analyzed in the special relativistic quantum regime, and compared with that of microcausality and the local commutativity of quantum fields. Its extrapolation to quantum general relativity on quantum bundles over curved spacetime is then described. It is shown that the resulting formulation of quantum-geometric locality based on the concept of local quantum frame incorporating a fundamental length embodies the key geometric and topological aspects of this concept. Taken in conjunction with the strong equivalence principle and the path-integral formulation of quantum propagation, quantum-geometric locality leads in a natural manner to the formulation of quantum-geometric propagation in curved spacetime. Its extrapolation to geometric quantum gravity formulated over quantum spacetime is described and analyzed.Comment: Mac-Word file translated to postscript for submission. The author may be reached at: [email protected] To appear in Found. Phys. vol. 27, 199

Microlocal sheaves and quiver varieties

We relate Nakajima Quiver Varieties (or, rather, their multiplicative version) with moduli spaces of perverse sheaves. More precisely, we consider a generalization of the concept of perverse sheaves: microlocal sheaves on a nodal curve X. They are defined as perverse sheaves on normalization of X with a Fourier transform condition near each node and form an abelian category M(X). One has a similar triangulated category DM(X) of microlocal complexes. For a compact X we show that DM(X) is Calabi-Yau of dimension 2. In the case when all components of X are rational, M(X) is equivalent to the category of representations of the multiplicative pre-projective algebra associated to the intersection graph of X. Quiver varieties in the proper sense are obtained as moduli spaces of microlocal sheaves with a framing of vanishing cycles at singular points. The case when components of X have higher genus, leads to interesting generalizations of preprojective algebras and quiver varieties. We analyze them from the point of view of pseudo-Hamiltonian reduction and group-valued moment maps.Comment: 49 page

Frontiers in complex dynamics

Rational maps on the Riemann sphere occupy a distinguished niche in the general theory of smooth dynamical systems. First, rational maps are complex-analytic, so a broad spectrum of techniques can contribute to their study (quasiconformal mappings, potential theory, algebraic geometry, etc.). The rational maps of a given degree form a finite-dimensional manifold, so exploration of this {\em parameter space} is especially tractable. Finally, some of the conjectures once proposed for {\em smooth} dynamical systems (and now known to be false) seem to have a definite chance of holding in the arena of rational maps. In this article we survey a small constellation of such conjectures centering around the density of {\em hyperbolic} rational maps --- those which are dynamically the best behaved. We discuss some of the evidence and logic underlying these conjectures, and sketch recent progress towards their resolution.Comment: 18 pages. Abstract added in migration