Exercise Sheet 3

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Exercise Sheet 3

• Exercise 7.
• ROLAP Algebra
• Assume that a fact table SalesCube has 3
  hierarchies with attributes
• ?ear ?, Month M, Productgroup P and City C and
  the measure
• sales. Assume that the attributes have the
  following cardinalities
• 3
• M 12
• P 500
• C 80
• Exercise 7.1
• Draw the aggregation network

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Exercise 7.2. Construct the ROLAP expression to
compute the average and maximal sales for the
groups ? ,P, ?, C and P Exercise
7.3 Translate the ROLAP expression of Exercise
7.2 into a single SQL statement and estimate its
cost total number of tuples read total
number of tuples written if you assume that there
is no optimization of this SQL statement. Exercis
e 7.4 Translate the SQL statement of Exercise
7.3 into several SQL statements employing
auxiliary tables for intermediate results. Try
to minimize the cost.
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Exercise 8 Clustering Exercise 8.1 Compute
the NN distances for the following set of points
and label the corresponding edges. A
D B C
Exercise 8.2 Compute the natural nearest
neighbor distances for the points of Exercise
8.1
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Exercise 8.3 Draw the minimal spanning tree for
the following set of points E F G
C D B A H I J
Exercise 8.4 Which clusters result, if we want
to have 2 clusters, 4 clusters, 5 clusters?
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Exercise 8.5 Which clusters result from the
k-means algorithm if we use the small circles as
starting centroids for the clusters? E F
G C o D o B A H I o o J