Undecidability in the Homomorphic Quasiorder of Finite Labeled Forests

Abstract. We prove that the homomorphic quasiorder of finite k-labeled forests has undecidable elementary theory for k 3, in contrast to the known decidability result for k = 2. We establish also undecidablity (again for every k 3) of elementary theories of two other relevant structures: the homomorphic quasiorder of finite k-labeled trees, and of finite k-labeled trees with a fixed label of the root element.

• Type: Conference
• Year: 2006
• Where: CIE
• Authors: Oleg V. Kudinov, Victor L. Selivanov
• Keywords: Applied Computing, CIE 2006, Finite K-labeled Forests, Finite K-labeled Trees, Undecidable Elementary Theory