Method for automatic wrapper repair

• US 20060085468A1
• Filed: 12/05/2005
• Published: 04/20/2006
• Est. Priority Date: 07/18/2002
• Status: Active Grant

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Chidlovskii, Boris
• Granted Patent: US 7,440,974 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/972 Access to data in other repository systems, e.g. legacy data or dynamic Web page generation
• CPC Class Codes: Y10S 707/99931 Database or file accessing
• CPC Class Codes: Y10S 707/99932 Access augmentation or optimizing
• CPC Class Codes: Y10S 707/99942 Manipulating data structure, e.g. compression, compaction, compilation
• CPC Class Codes: Y10S 707/99945 Object-oriented database structure processing
• CPC Class Codes: Y10S 707/99948 Application of database or data structure, e.g. distributed, multimedia, or image

Abstract

A method of information extraction from a Web page using an initial wrapper which has become partially inoperative, wherein the initial wrapper comprises an initial set of rules for extracting information and for assigning labels from a wrapper set of labels to the extracted information, includes using the initial set of rules to extract strings from the Web page parsed in forward direction; analyzing the extracted strings according to the initial set of rules for assigning labels associated with the wrapper; assigning labels to those strings which satisfy the label rules; using the initial set of rules to extract strings from the Web page in backward/(opposite) direction; analyzing the extracted strings according to the set of rules for assigning labels associated with the wrappers; and assigning labels to those unlabeled strings from which satisfy the label rules.

Claims

1. A method of information extraction from a Web page using an initial wrapper which has become partially inoperative, comprising:

wherein the initial wrapper comprises an initial set of rules for extracting information and for assigning labels from a wrapper set of labels to the extracted information;

extracting strings from the Web page parsed in forward direction using the initial set of rules;

analyzing the extracted strings according to the initial set of rules for assigning labels associated with the wrapper;

assigning labels to those strings which satisfy the label rules;

extracting strings from the Web page in backward/(opposite) direction using the initial set of rules;

analyzing the extracted strings according to the set of rules for assigning labels associated with the wrappers; and

assigning labels to those unlabeled strings from which satisfy the label rules.

2. The method of claim 1, further comprising:

classifying the extracted strings based on content features of the labeled extracted strings from the forward direction; and

validating those labeled extracted strings which satisfy the label rules within some first threshold value.

3. The method of claim 2, further comprising:

classifying the extracted strings based on content features of the labeled extracted strings from the backward direction; and

validating those labeled extracted strings which satisfy the label rules within some second threshold value.

4. The method of claim 1, wherein the initial wrapper W comprises a triple (T, L, R), where T is an input tokenizer, L is a semantic label set and R is a set of extraction rules R={r_i}, where each rule r_i is a triple (p,s,l), where p ε

S¹ and s ε

S^u are prefix and suffix, and 1 ε

L.

5. The method of claim 4, wherein wrapper W parses the Web page from the beginning to the end;

wherein the extraction rules in R comprise;

for a current textual token t, a labeled prefix P of t contains all tokens from the beginning until t, with all previous textual tokens labeled, and S is suffix of t, E=PtS, P ε

S¹, S ε

S^u, and a pair (p,s) forms the full context of token t;

comparing P and S to prefixes and suffixes in the extraction rules such that a Pair (P,S) matches a prefix-suffix pair (p,s) of a rule r=(p,s,l), if p is a suffix of P, P=up, and s is a prefix of S, S=sv, for some labeled u and unlabeled v;

if a match is found, string t is labeled with label 1 in the rule; and

if no exact rule is found for P and S, the wrapper results in an error.