The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 17, 1996
Filed:
Sep. 08, 1994
Allen L Brown, Jr, San Diego, CA (US);
Sidney W Marshall, Penfield, NY (US);
Xerox Corporation, Stamford, CT (US);
Abstract
Some document languages such as the Standard Generalized Markup Language (SGML) represent documents as trees with each node of the tree labelled with a tag and each node's immediate descendants taken in order having tags that satisfy a production corresponding to the parent's tag. Thus, a document is represented as a complete parse tree satisfying the production rules of a grammar. To simplify maintaining a valid document/parse tree at all stages, an efficient check is made whether a document is valid or can be extended to a valid document and furthermore to show how a document could be changed to be valid. A document can be extended to a valid document if is equal to a valid document with possibly some nodes deleted. External (leaf) nodes can just be deleted. Internal nodes are deleted by replacing the arc from the parent with multiple arcs (in the same order) from the parent to each of the children of the deleted node. A grammar is constructed from the given grammar that includes those documents that can be completed to a valid document and is called a gapped grammar. A method is provided to teach how a gapped grammar can be constructed from a grammar, a parser/checker is efficiently implemented.