Annotated reasoning

The application of deduction in various domains resulted in a variety of different techniques to guide the proof search. Many of these techniques incorporate additional knowledge to restrict or select possible proof steps. As a consequence, usually the underlying calculus has to be modified to keep track of this information during the proof search. In this paper we present a general framework for maintaining additional strategic knowledge within a proof. We introduce a formal notion of annotations attached to the constituents of formulas and illustrate how a generic method of inheriting these annotations can be instantiated for various purposes. This revised version was published online in June 2006 with corrections to the Cover Date.     

Über die Altersbestimmung von Eichenholz in Norddeutschland mit Hilfe der Dendrochronologie

Zusammenfassung Die M?glichkeiten einer Alterbestimmung von Eichenholz in Norddeutschland mit Hilfe der dendrochronologischen Methode wurden an einigen Beispielen aufgezeigt und er?rtert. Daraus kann man folgern, da? eine dem Süden entsprechende Standardkurve für Norddeutschland nicht aufgebaut werden kann. Eine erfolgreiche Absolutdatierung ist meist nur mit Hilfe von gesicherten, streng standort-bezogenen Kurven durchführbar. Aber auch Relativdatierungen geben h?ufig genügend Aufschlu?. Die Altersbestimmungen der Klosteranlage Wienhausen/Celle bzw. der ausgegrabenen Siedlung Haithabu mit Hilfe norddeutscher Standortchronologien zeigen den Wert und die M?glichkeit der dendrochronologischen Datierung in Norddeutschland. Mitunter k?nnen Absolutdatierungen auch mit der süddeutschen Standardkurve erfolgen, wenn n?mlich Holz aus südlicheren Gegenden in Norddeutschland verbaut wurde. Auf diese Weise lie? sich die Bauzeit der mittelalterlichen Bremer Kogge ermitteln.

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On the dating of oakwood in Northern Germany by the dendrochronological method

Summary The possibilities of dating oakwood by the dendrochronological method have been demonstrated and discussed in relation to specimens from various sites in Northern Germany. It has been shown that a standard growth-ring series, such as that corresponding to the whole of Southern Germany, cannot be established for Northern Germany. In most cases a successful dating can be realized only by means of a definite growth-ring series related to a narrow site. However, the correlation between older and younger materials often procides sufficient information. The determination of the age of the monastry in Wienhausen/Celle and of the excavated settlement Haithabu illustrates the value and the possibilities of dendrochronology in Northern Germany. Absolute dating occasionally may be possible with the standard growth-ring series of Southern Germany; namely where wood from southern regions has been used in Northern Germany. In this way the date of construction of the Bremer Kogge was determined.

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Herrn Prof. Dr. Hans Mayer-Wegelin zur Vollendung des 70. Lebensjahres gewidmet.     

The planning of Berlin's city and historic centre

Since the fall of the Wall, there has been heavy international investment in building in East Berlin. On the whole, efforts have remained marginal. Only the western part of East Berlin with its baroque grid has been developed. The central and eastern parts remain as they were. The planning for City East follows four main criteria: to redefine the historic core by structural means without resort to architectural pastiche; to redesign the major roads which occupy much of the historic centre; to restructure the modernism of the GDR capital without demolishing the (mainly prefabricated) buildings; to form an idea of the third town which would be developed by merging existing features with our new plan.     

The potential of runoff-farming in the Sahel region: Developing a methodology to identify suitable areas

Runoff-farming, a water harvesting technique, is the diversion of rain water from a collecting area to a cropping area, thereby increasing the quantity of water available for crop growth. This technique, applicable in various types, is regarded as necessary to secure and increase food production in semi-arid regions. Simultaneously it minimizes water erosion risk where it is applied. As the potential of runoff-farming has not been investigated, a methodology had to be developed to enable planners to identify suitable areas the most efficient way. Five main information sources are tapped: ground checks by various specialists, maps, data, aerial photographs and satellite images. The interpretation of the collected data yields in the quantification of the runoff water, the water requirements of the crops and the water storage capacity of the soil. All factors have to be validated and integrated into a decision model.     

Reference values of the chronoamperometric response at cylindrical and capped cylindrical electrodes

This work provides accurate solutions of the cylinder flux function I(0,1;T), first solved by Jaeger and Clarke, which can serve as reference values for electrochemical amperometric diffusion limited currents at a cylinder, as well as heat fluxes under equivalent conditions (fixed temperature at the cylinder surface). For the capped cylinder of varying lengths, reference values of time-dependent electrochemical currents are provided. Steady state currents at capped cylinders are presented and a function is provided that fits the simulated values to within 1%. All of these are more accurate than in previous works.