Browsing by Author "Samuelsson, Erik"

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    Gräfsnäs dolda skatter
    (2009-11-23T19:23:32Z) Samuelsson, Erik; University of Gothenburg/Department of Conservation; Göteborgs universitet/Institutionen för kulturvård
    This paper examines how to use different kinds of source material for building surveys. The study examines how to use legends, construction archaeological surveys and Ground Penetrating Radar (GPR) as source material, and use them against each other to ensure the reliability they have. As a starting point I used Gräfsnäs castle ruin in Alingsås, Sweden, as an example. Gräfsnäs castle was probably built in the Middle Ages and was rebuilt through the ages until it became a ruin in the late 1800s. The castle ruin is today Alingsås most visited attraction. The investigation has focused on three areas which are located in the very ruin; rescue tunnels, the cellar vault and the treasure. There are legends that describe how the castle lord of Gräfsnäs fled an attack of the Danes in 1612 in a rescue tunnel which ended at the beach. At the construction archaeological surveys carried out in 1935-36 they found a sewer in the courtyard that was once served as rescue tunnel and ended in the moat. The GPR survey conducted in March 2008 located the rescue tunnel is probably still intact on the part of its former extent. Another legend describes that they found the cellar vault when they broke down the remnants of wings in the courtyard. Under a tower barrels of beer were found in the cellar and the legend said to be "very tasty". The construction archaeological surveys found residues of the tower, but no observations were made of some cellar vault. GPR study found several architectural remnants in the courtyard - such as floor levels and a well but no cellar vault was located. The third described legends about a "tremendous treasure" which is said to be buried in entrance hall. The construction of archaeological excavations dug no more than a ditch in entrance hall so it located no treasure here. GPR investigation argues that in the middle of entrance hall is a large unknown object. The thesis shows that in many cases there is evidence it is likely that there is something behind the legends which were examined. By using multiple data sources together we can reach new understanding of Gräfsnäs castle ruin.
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    Hur vet vi att ett datorprogram gör vad det säger att det gör? Formell verifiering av hypergeometriska rekursionsrelationer med polynomkoefficienter
    (2025-03-12) Dao, Louis; Davoodi, Anna; Samuelsson, Erik; University of Gothenburg/Department of Mathematical Science; Göteborgs universitet/Institutionen för matematiska vetenskaper
    Detta arbete använder formell verifiering för att undersöka loopar inom programmering. Looparna som behandlas ses ekvivalent som hypergeometriska rekursionsrelationer. Arbetet undersöker om lösningen un till dessa hypergeometriska rekursionsrelationer med polynomkoefficienter alltid är heltalsvärd. Detta genomförs under antagandet att startvärdet för rekursionsrelationen alltid är 1. För koefficienter som är vissa typer av linjära polynom ges villkor som avgör om un alltid är ett heltal. Även mer involverade typer av polynom undersöks, där en explicit algoritm ges som avgör om un alltid är ett heltal efter ändligt antal steg. Resultaten för det sistnämnda fallet generaliseras även till flera variabler.