Florentin Neumann

Variations of the turing test in the age of internet and virtual reality

Inspired by Hofstadters Coffee-House Conversation (1982) and by the science fiction short story SAM by Schattschneider (1988), we propose and discuss criteria for non-mechanical intelligence: We emphasize the practical requirements for such tests in view of massively multiuser online role-playing games (MMORPGs) and virtual reality systems like Second Life. In response to these new needs, two variations (Chomsky-Turing and Hofstadter-Turing) of the original Turing-Test are defined and reviewed. The first one is proven undecidable to a deterministic interrogator. Concerning the second variant, we demonstrate Second Life as a useful framework for implementing (some iterations of) that test.

On the spanning ratio of partial Delaunay triangulation

Partial Delaunay triangulation (PDT) is a well-known subgraph construction that has already been used for years in the context of geographic routing and topology control. So far, it has been unknown if partial Delaunay triangulation is a network spanner. Network spanners are those subgraph constructions which maintain the length of the shortest path between any pair of nodes up to a constant factor. This factor is also referred to as the spanning ratio. In this work we prove that partial Delaunay triangulation is a network spanner for unit disk graphs. Furthermore, from our proof follows immediately that the spanning ratio of PDT is less than or equal to 1+√5/4 π2.

Path Properties and Improvements of Sweep Circle Traversals

The rotational sweep algorithm (RS) solves the beaconless recovery problem in local minimum situations, which occur during Greedy routing. It routes a data packet around a void region using only two additional messages per hop, while guaranteeing packet delivery. In this context we present three related contributions: (1) When a sweep circle (SC) is used for RS, the resulting path coincides with the corresponding partial Delaunay triangulation Face traversal. Hence, SC traversals use edges of an Euclidean spanner and are therefore potentially very short. (2) We contrast this result by giving examples where RS performs particularly bad, when considering the Hop instead of the Euclidean metric. (3) To cope with this discrepancy, we devise a beaconless algorithm that helps to cut short in such situations and thereby helps to avoid unnecessary routing steps.

RSSI-based localization of a wireless sensor node with a flying robot

We consider the problem of navigating a flying robot to a specific sensor node within a wireless sensor network. This target sensor node periodically sends out beacons. The robot is capable of sensing the received signal strength of each received beacon (RSSI measurements). Existing approaches for solving the sensor spotting problem with RSSI measurements do not deal with noisy channel conditions and/or heavily depend on additional hardware capabilities. In this work we reduce RSSI fluctuations due to noise by continuously sampling RSSI values and maintaining an exponential moving average (EMA). The EMA values enable us to detect significant decrease of the received signal strength. In this case it is reasoned that the robot is moving away from the sensor. We present two basic variants to decide a new moving direction when the robot moves away from the sensor. Our simulations show that our approaches outperform competing algorithms in terms of success rate and flight time. In field experiments with real hardware, a flying robocopter successfully and quickly landed near a sensor placed in an outdoor test environment. Traces show robustness to additional environmental factors not accounted for in our simulations.

Short Paper: Structural Network Properties for Local Planarization of Wireless Sensor Networks

Network graphs satisfying redundancy and coexistence can be planarized by means of local algorithms without making assumptions on the nodes’ communication ranges. We generalize these properties to k -weak and k-strong coexistence and redundancy. Subsequently, we give empirical evidence that these properties are present in simulated wireless sensor networks as well as in actual testbed deployments, especially if looking at the graph’s c-hop clustered overlay representations, for \(c\le 2\).

On Demand Beaconless Planar Backbone Construction for Quasi Unit Disk Graphs

Beaconless topology control algorithms reduce message overhead of local topology constructions compared to conventional (beacon-based) local approaches by avoiding maintenance of neighborhood tables. Moreover, they construct a nodes adjacency in the desired topology on demand and only locally, i.e., Do not require network-wide operation. In this work, we present a beaconless topology control algorithm which enables a node to reactively construct a planar backbone graph in its geographic vicinity. This backbone graph is a constant node degree, constant stretch hop-spanner for the input quasi unit disk graph. Our contribution is novel, since all known algorithms with comparable outputs require maintenance of neighborhood tables and are designed for network-wide operation. In addition, it is of significance since there are several applications of it, e.g., In the context of geographic unicast and multicast routing with guaranteed delivery.

Partial delaunay triangulation-based asynchronous planarization of quasi unit disk graphs

We present a distributed and fully asynchronous algorithm for construction of the partial Delaunay triangulation over quasi unit disk graphs. Provided that the ratio of the maximum to the minimum communication range of nodes is bounded from above by square root of two, our algorithm outputs a connected and planar overlay graph of the input graph, which enables the use of localized geographic routing algorithms that guarantee message delivery. Moreover, under the assumption that the input graph is civilized (i.e., any two network nodes have non-zero minimum Euclidean distance), we show that our algorithm is localized. We show by means of simulation that our approach yields output graphs whose Euclidean spanning ratio is on average significantly smaller compared to those constructed by all other asynchronous approaches.