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Author

K. Zhang

Bio: K. Zhang is an academic researcher from University of Western Ontario. The author has contributed to research in topics: Heuristics & Hill climbing. The author has an hindex of 1, co-authored 1 publications receiving 6 citations.

Papers
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Proceedings ArticleDOI
10 Nov 1992
TL;DR: The problem of comparison between unordered trees, i.e. trees for which the order among siblings is unimportant, is considered and an enumerative algorithm and several heuristics leading to approximate solutions are given.
Abstract: The problem of comparison between unordered trees, i.e. trees for which the order among siblings is unimportant, is considered. The criterion for comparison is the distance as measured by a weighted sum of the costs of deletion, insertion, and relabel operations on tree nodes. Such comparisons may contribute to pattern recognition efforts in any field (e.g. genetics) where data can naturally be characterized by unordered trees. It is observed that the problem is NP-complete. An enumerative algorithm and several heuristics leading to approximate solutions are given. The algorithms are based on probabilistic hill climbing and bipartite matching techniques. The accuracy and time efficiency of the heuristics are evaluated by applying them to a set of trees transformed from industrial parts based on a previously proposed morphological model. >

6 citations


Cited by
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Patent
Charles Simonyi1
27 Jun 1997
TL;DR: In this paper, the programmer creates an intentional program tree using a syntax-independent editor, which allows the program to select in which programming language the computer program is to be displayed, rather than an implementation of the programmer's intent.
Abstract: A method and system for generating a computer program in the manner that uses no computer programming language syntax. The system represents a computer program as an intentional program tree, which is a high-level program tree that is a syntax-independent representation using high-level computational constructs. The intentional program tree represents a programmer's intent, rather than an implementation of the programmer's intent. The programmer creates an intentional program tree using a syntax-independent editor. The editors allows a programmer to directly manipulate the intentional program tree. Because the program is stored as an intentional program tree in a syntax-independent manner, the editor allows the program to select in which of a various programming language the computer program is to be displayed. In addition, the system transforms an intentional program tree to a reduced program tree, which is a program tree comprising low-level computational constructs, in a process called reduction. The reduction process replaces expressions of programmer's intents with a representation of one of possible multiple implementations of those intents using low-level computational constructs.

70 citations

Patent
Ted J. Biggerstaff1
12 Sep 1997
TL;DR: In this article, a method and system for anticipatory optimization of computer programs is presented, which generates code for a program that is specified using programming-language-defined computational constructs and user-defined, domain-specific computational constructs.
Abstract: A method and system for anticipatory optimization of computer programs. The system generates code for a program that is specified using programming-language-defined computational constructs and user-defined, domain-specific computational constructs. The system generates an abstract syntax tree (AST) representation of the program. The AST has nodes representing the computational constructs of the program. For each user-defined, domain-specific computational construct, the system determines whether a user-defined, domain-specific transform has been defined for the computational construct. The transform transforms a portion of the AST relating to the user-defined, domain-specific computational construct into one or more programming-language-defined computational constructs. When a domain-specific transform has been defined for the computational construct, the system transforms the AST in accordance with the domain-specific transform. The transformed AST is in a form that reflects an optimization of the programming-language-defined computational constructs based on the user-defined, domain-specific computational construct.

51 citations

Journal ArticleDOI
TL;DR: It is shown that no efficient algorithm can solve either variant of the AGM unless P = NP, and several heuristic algorithms leading to approximate solutions are presented, based on probabilistic hill climbing and maximum flow techniques.

44 citations

Patent
Charles Simonyi1
26 Oct 1994
TL;DR: In this article, a method and system for generating executable code for a computer program is described, where a programmer creates an intentional program tree using a syntax-independent editor, which allows a programmer to directly manipulate the intentional program trees.
Abstract: A method and system is described for generating executable code for a computer program. A programmer creates an intentional program tree using a syntax-independent editor. The editor allows a programmer to directly manipulate the intentional program tree. The intentional program tree has nodes. Each node represents a high-level computational construct of the computer program. For each node representing a high-level computational construct, the system transforms the node into an implementation of the high-level computational construct using low-level computational constructs. For each node representing a low-level computational construct, the system generates executable code that implements the low-level computational construct. The system further provides that where a high-level computational construct has a plurality of implementations of the high-level computational construct, the system transforms the nodes by selecting one of the implementations and transforms the node in accordance with the selected implementation. The system further provides that the implementation is selected by automatically analyzing semantics of the intentional program tree.

44 citations

Journal ArticleDOI
TL;DR: This paper proposes a new top-down method for mining unordered closed tree patterns from a database of trees such that every mined pattern must contain a common piece of information in the form of a tree specified by the user.
Abstract: Mining frequent tree patterns from tree databases has practical importance in domains like Web mining, Bioinformatics, and so on. Although there have been algorithms on efficient tree mining, these algorithms are often lack of the interpretability in that they often produce a huge number of patterns, most of which are meaningless to users. This paper aims at both demands, one with respect to computational cost, which is efficient generation of tree patterns, and another one with respect to the interpretability. This task requires an efficient method to incorporate the users' needs into mining process. We propose a new top-down method for mining unordered closed tree patterns from a database of trees such that every mined pattern must contain a common piece of information in the form of a tree specified by the user. This type of mining is called mining with subtree constraint which would be useful, for example, inWeb mining and Bioinformatics, where users want to extract common patterns around some given information from original data. The proposed algorithm is tested and compared with a state-of-the-art tree mining algorithm on real and artificial datasets with very good results.

3 citations