Friedhelm Meyer auf der Heide

Efficient PRAM simulation on a distributed memory machine

We present a randomized simulation of a <italic>n</italic>log log (<italic>n</italic>) log (<italic>n</italic>)-processor shared memory machine (DMM) with optimal expected delay O(log log (<italic>n</italic>)) per step of simulation. The time bound for the delay is guaranteed with overwhelming probability. The algorithm is based on hashing and uses a novel simulation scheme. The best previous simulations use a simpler scheme based on hashing and have much larger expected delay: &THgr;(log(<italic>n</italic>)/log log (<italic>n</italic>)) for the simulation of an <italic>n</italic>-processor PRAM on an <italic>n</italic> processor DMM, and &THgr;(log(<italic>n</italic>)) in the case where the simulation preserves the processor-time product.

The randomized z-buffer algorithm: interactive rendering of highly complex scenes

We present a new output-sensitive rendering algorithm, the randomized z-buffer algorithm. It renders an image of an arbitrary three-dimensional scene consisting of triangular primitives by reconstruction from a dynamically chosen set of random surface sample points. This approach is independent of mesh connectivity and topology. The resulting rendering time grows only logarithmically with the numbers of triangles in the scene. We were able to render walkthroughs of scenes of up to 1014 triangles at interactive frame rates. Automatic identification of low detail scene components ensures that the rendering speed of the randomized z-buffer cannot drop below that of conventional z-buffer rendering. Experimental and analytical evidence is given that the image quality is comparable to that of common approaches like z-buffer rendering. The precomputed data structures employed by the randomized z-buffer allow for interactive dynamic updates of the scene. Their memory requirements grow only linearly with the number of triangles and allow for a scene graph based instantiation scheme to further reduce memory consumption.

Algorithms — ESA 2001

Many modern applications store and process datasets much larger than the main memory of even state-of-the-art high-end machines. Thus massive and dynamically changing datasets often need to be stored in data structures on external storage devices, and in such cases the Input/Output (or I/O) communication between internal and external memory can become a major performance bottleneck. In this paper we survey recent advances in the development of worst-case I/O-efficient external memory data structures.

Energy, congestion and dilation in radio networks

We investigate the problem of path selection in radio networks for a given set of sites in two-dimensional space. For some given static point-to-point communication demand we define measures for congestion, energy consumption and dilation that take interferences between communication links into account.We show that energy optimal path selection for radio networks can be computed in polynomial time. Then, we introduce the diversity

A new universal class of hash functions and dynamic hashing in real time

g(V)

Truly efficient parallel algorithms: 1-optimal multisearch for an extension of the BSP model

of a set

Dynamic load balancing in distributed hash tables

V\subseteq \REAL^2

Universal algorithms for store-and-forward and wormhole routing

. It can be used to upperbound the number of interfering edges. For real-world applications it can be regarded as

A tight runtime bound for synchronous gathering of autonomous robots with limited visibility

\Theta(\log n)

Simple, efficient shared memory simulations

. A main result of the paper is that a weak