Subsets close to invariant subsets for group actions

• Main Authors: Brailovsky, Leonid., Pasechnik, Dmitrii V., Praeger, Cheryl E.
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2011
• Subjects: DRNTU::Science::Mathematics::Applied mathematics
• Online Access: https://hdl.handle.net/10356/93782; http://hdl.handle.net/10220/6800
• Institution: Nanyang Technological University

Let G be a group acting on a set Ω and k a non-negative integer. A subset (finite or infinite) A ⊆ Ω is called k-quasi-invariant if |Ag \ A| ≤k for every g ∈ G. It is shown that if A is k-quasi-invariant for k ≥1 , then there exists an invariant subset Γ⊆Ω such that |A Δ Γ | < 2ek [(In 2k)]. Info...