HMM-based Artificial Designer for Search Interface Segmentation
HMM-based Artificial Designer for
Search Interface Segmentation
Ritu Khare, Yuan An, Il-Yeol Song
ACCESSING THE DEEP WEB
HMM: ARTIFICIAL DESIGNER
Deep Web: Data that exist on the Web but are not
returned by search engines through traditional crawling
An HMM (Hidden Markov Model) can act like a human designer
who has the ability to design an interface using acquired
knowledge and to determine (decode) the segment boundaries
and semantic labels of components.
Accessing Deep Web contents: The primary way to
access this data (by manually filling up HTML forms on
search interfaces ) is not scalable.
Hence, more sophisticated solutions, such as designing
meta-search engines or creating dynamic page
repositories, are required. A pre-requisite to these
solutions is an understanding of the search interfaces.
Interface Segmentation is an important portion of the
problem of search interface understanding.
Fig 2. Simulating a Human
Designer using HMMs
The designing process is similar to statistically choosing one
component from a bag of components (a superset of all possible
components) and placing it on the interface while keeping the
semantic role (attribute-name, operand, or operator) of the
component in mind. See Figure 2.
Fig 4. Learnt Topology of semantic labels
Segment /Logical Attribute
86 05 %
e.g., between “D19Mit32” and “Tbx10”
e.g., “10.0 -40.0”
Fig 1. Segmented Interface
(segments marked by dotted lines)
While a user
is naturally trained to perform
segmentation, a machine is unable to “see” a segment
due to the following reasons:
1. The components that are visually close to each other
might be located very far apart in the HTML source
2. A machine does not implicitly have any search
experience that can be leveraged to identify a
segment ‘ b
t ‘s boundary.
Research Question: How can we make a machine learn
how to segment an interface?
2-LAYERED HMM APPROACH
The problem of decoding is two-folded: 1) Segmentation, 2)
Assignment of semantic labels to components. Hence, a 2-layered
HMM is employed as shown in Figure 3. The first layer T-HMM
tags each component with appropriate semantic labels (attributeg
name, operator, and operand). The second layer S-HMM
segments the interface into logical attributes.
Fig 3. 2-Layered HMM Architecture
200 interfaces from Biology Domain
DOM-trees of components
Maximum Likelihood Method
1 This approach outperforms LEX a contemporary
heuristic-based method, and achieves a 10%
improvement in segmentation accuracy.
2. This is the first work to apply HMMs on deep Web
search interfaces. HMMs helped in incorporating the
first-hand knowledge of the designer to perform
1. To recover the schema of deep Web databases by
extraction of finer details such as data type and
constraints of logical attribute.
2. To test this approach on interfaces from other
domains, given the diverse domain distribution of
the deep Web
3. To investigate the use of the use of Baum Welch
training algorithm to minimize the degree of