Describing Graphs: A First-Order Approach to Graph Canonization
Describing Graphs: A First-Order Approach to Graph Canonization
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描述图:图规范化的一阶方法
DOI:
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发表时间:
1990
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通讯作者:
E. Lander
中科院分区:
文献类型:
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作者:
N. Immerman;E. Lander
In this paper we ask the question, “What must be added to first-order logic plus least-fixed point to obtain exactly the polynomial-time properties of unordered graphs?” We consider the languages L k consisting of first-order logic restricted to k variables and C k consisting of L k plus “counting quantifiers”. We give efficient canonization algorithms for graphs characterized by C k or L k . It follows from known results that all trees and almost all graphs are characterized by C 2.