The cosmological constant problem is examined under the assumption that the extrinsic curvature of the space-time contributes to the vacuum. A compensation mechanism based on a variable cosmological term is proposed. Under a suitable hypothesis on the behavior of the extrinsic curvature, we find that an initially large Λ(t) rolls down rapidly to zero during the early stages of the universe. Using perturbation analysis, it is shown that such vacuum behaves essentially as a spin-2 field which is independent of the metric.

We survey the current state of the art in geometric constraint solving. Both 2D and 3D constraint solving is considered, and different approaches are characterized.

We report on the development of a two-dimensional geometric constraint solver. The solver is a major component of a new generation of CAD systems that we are developing based on a high-level geometry representation. The solver uses a graph-reduction directed algebraic approach, and achieves

Finding the configurations of a set of rigid bodies that satisfy a set of geometric constraints is a problem traditionally solved by reformulating the geometry and constraints as algebraic equations which are solved symbolically or numerically. But many such problems can be solved by reasoning

We survey the current state of the art in geometric constraint solving. Both 2D and 3D constraint solving is considered, and different approaches are characterized.

Abstract — Geometrical constraint in grasping, which is as known as caging, gives some advantages over conventional force-controlled grasping. For the difficulty of achievement of complete caging from the limitation of DOF of the hand, we propose partial caging, where the object is partly

Modelling by geometric constraints is a promising method in the field of CAD/CAM. However, this process, closely related to computer programming, is also prone error. A geometric constraints based modeller should help the end user to find his mistakes , or, better, not to commit ones by watching

. To enrich the shape vocabulary of mechanical CAD systems, we develop techniques that allow defining free-form curves from geometric constraints. An important aspect of this aproach is the ability to obtain all possible instances of curve segments satisfying the constraints of a dimensioned sketch

We present a flow-based method for decomposing the graph of a geometric constraint problem. The method fully generalizes degree-of-freedom calculations, prior approaches based on matching specific subgraph patterns, as well as prior flow-based approaches. Moreover, the method generically iterates

This paper presents a new incremental approach to geometric constraint satisfaction that is tailored to interactive applications. Our approach categorizes solutions into geometric primitives representing a range of solutions with uniform geometric characteristics. This scheme keeps intermediate