ISCHIA GROUP THEORY 2016, March 29th–April 2nd Groups of rational interval exchange transformations Agnieszka Bier and Vitaliy Sushchanskyy Institute of Mathematics, Silesian University of Technology, Poland
[email protected] Interval exchange transformations Rational interval exchange transformations Subgroups of RIET defined by supernatural numbers Let I denote the half-open interval [0 , 1) and let An interval exchange transformation f = ( π, σ ) ∈ IET defined by the rational partition π = {a0, a 1, ..., a n} where all ai are rational numbers is called rational iet . The subset In particular, if f = ( πni, σ ) ∈ RIET( ni) and ni+1 = k · ni then the diagonal embedding π = {a0, a 1, ..., a n}, 0 = a0 ≤ ai < a i+1 ≤ an = 1 of all rational iets is a subgroup of IET, which we denote by RIET. ϕi is defined by the following rule: Every rational interval exchange transformation may be considered as a transformation be a partition of I into n subintervals [ a , a ), i = 0 , ..., n − 1. A left-continuous l · n + j l · n + j + 1 l · n + σ(j) l · n + σ(j) + 1 i i+1 defined by the partition π of interval I into n subintervals of equal length. f ϕi i , i = i , i , bijection f : [0 , 1) → [0 , 1) acting as piecewise translation, i.e. shuffling the subintervals n pi ni+1 ni+1 ni+1 ni+1 If f = ( π, σ ), where π = {0, a , ..., a n , 1}, where ai = ∈ Q, is a ratio- [ai, a i+1 ), is called an interval exchange transformation (iet) of I.