1 (* Title: thys/Abacus.thy

     1 (* Title: thys/Abacus.thy

     2    Author: Jian Xu, Xingyuan Zhang, and Christian Urban

     2    Author: Jian Xu, Xingyuan Zhang, and Christian Urban

     3 *)

     4 *)

     4 

     5 

     5 chapter {* Abacus Machines *}

     6 chapter {* Abacus Machines *}

     6 

     7 

     7 theory Abacus

     8 theory Abacus