627 research outputs found
Mining Multiple Related Tables Using Object-Oriented Model
An object-oriented database is represented by a set of classes connected by their class inheritance hierarchy through superclass and subclass relationships. An object-oriented database is suitable for capturing more details and complexity for real world data. Existing algorithms for mining multiple databases are either Apriori-based or machine learning techniques, but are not suitable for mining multiple object-oriented databases.
This thesis proposes an object-oriented class model and database schema, and a series of class methods including that for object-oriented join ( OOJoin) which joins superclass and subclass tables by matching their type and super type relationships, mining Hierarchical Frequent Patterns ( MineHFPs) from multiple integrated databases by applying an extended TidFP technique which specifies the class hierarchy by traversing the multiple database inheritance hierarchy. This thesis also extends map-gen join method used in TidFP algorithm to oomap-gen join for generating k-itemset candidate pattern to reduce the candidate itemset generation by indexing the (k-1)-itemset candidate pattern using two position codes of start position and end position codes tied to inheritance hierarchy level. Experiments show that the proposed MineHFPs algorithm for mining hierarchical frequent patterns is more effective and efficient for complex queries
GCG: Mining Maximal Complete Graph Patterns from Large Spatial Data
Recent research on pattern discovery has progressed from mining frequent
patterns and sequences to mining structured patterns, such as trees and graphs.
Graphs as general data structure can model complex relations among data with
wide applications in web exploration and social networks. However, the process
of mining large graph patterns is a challenge due to the existence of large
number of subgraphs. In this paper, we aim to mine only frequent complete graph
patterns. A graph g in a database is complete if every pair of distinct
vertices is connected by a unique edge. Grid Complete Graph (GCG) is a mining
algorithm developed to explore interesting pruning techniques to extract
maximal complete graphs from large spatial dataset existing in Sloan Digital
Sky Survey (SDSS) data. Using a divide and conquer strategy, GCG shows high
efficiency especially in the presence of large number of patterns. In this
paper, we describe GCG that can mine not only simple co-location spatial
patterns but also complex ones. To the best of our knowledge, this is the first
algorithm used to exploit the extraction of maximal complete graphs in the
process of mining complex co-location patterns in large spatial dataset.Comment: 1
A Model-Based Frequency Constraint for Mining Associations from Transaction Data
Mining frequent itemsets is a popular method for finding associated items in
databases. For this method, support, the co-occurrence frequency of the items
which form an association, is used as the primary indicator of the
associations's significance. A single user-specified support threshold is used
to decided if associations should be further investigated. Support has some
known problems with rare items, favors shorter itemsets and sometimes produces
misleading associations.
In this paper we develop a novel model-based frequency constraint as an
alternative to a single, user-specified minimum support. The constraint
utilizes knowledge of the process generating transaction data by applying a
simple stochastic mixture model (the NB model) which allows for transaction
data's typically highly skewed item frequency distribution. A user-specified
precision threshold is used together with the model to find local frequency
thresholds for groups of itemsets. Based on the constraint we develop the
notion of NB-frequent itemsets and adapt a mining algorithm to find all
NB-frequent itemsets in a database. In experiments with publicly available
transaction databases we show that the new constraint provides improvements
over a single minimum support threshold and that the precision threshold is
more robust and easier to set and interpret by the user
Interactive Data Exploration with Smart Drill-Down
We present {\em smart drill-down}, an operator for interactively exploring a
relational table to discover and summarize "interesting" groups of tuples. Each
group of tuples is described by a {\em rule}. For instance, the rule tells us that there are a thousand tuples with value in the
first column and in the second column (and any value in the third column).
Smart drill-down presents an analyst with a list of rules that together
describe interesting aspects of the table. The analyst can tailor the
definition of interesting, and can interactively apply smart drill-down on an
existing rule to explore that part of the table. We demonstrate that the
underlying optimization problems are {\sc NP-Hard}, and describe an algorithm
for finding the approximately optimal list of rules to display when the user
uses a smart drill-down, and a dynamic sampling scheme for efficiently
interacting with large tables. Finally, we perform experiments on real datasets
on our experimental prototype to demonstrate the usefulness of smart drill-down
and study the performance of our algorithms
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