Christian Hidber

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D ata analysis is fundamentally an iterative process in which you issue a query, receive a response, formulate the next query based on the response, and repeat. You usually don’t issue a single, perfectly chosen query and get the information you want from a database; indeed, the purpose of data analysis is to extract unknown information, and in most(More)
We present a novel algorithm to compute large itemsets online. The user is free to change the support threshold any time during the first scan of the transaction sequence. The algorithm maintains a superset of all large itemsets and for each itemset a shrinking, deterministic interval on its support. After at most 2 scans the algorithm terminates with the(More)
We present an integration of Mathematica into Prolog using MathLink. We illustrate the interplay between the di erent components by evaluating a simple example. The motivation based on algebraic modeling as well as an application from combinatorial group theory are brie y sketched.
We show that amalgams of nitely generated torsionfree nilpotent groups of class c along a cyclic subgroup satisfy a polynomial isoperimetric inequality of degree 4c. The distortion of the amalgamated subgroup is bounded above by a polynomial of degree c. We also give an example of a non-cyclic amalgam of nitely generated torsionfree nilpotent groups along(More)
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