[GAP Forum] (no subject)

[NIK NIK]

Dear GAP Forum:

I work with “Automata” package and find interesting thing:

gap> ab_star:=RationalExpression("(aUb)*");
(aUb)*

gap> aut_star:=RatExpToNDAut( ab_star );
< non deterministic automaton on 2 letters with 3 states >
gap> Display(aut_star);
   |  1       2       3
---------------------------
 a | [ 1 ]   [ 1 ]   [ 1 ]
 b | [ 2 ]   [ 2 ]   [ 2 ]
Initial state:    [ 3 ]
Accepting states: [ 1, 2, 3 ]

gap> daut_star:=RatExpToAut( ab_star );
< deterministic automaton on 2 letters with 1 states >
gap> Display(daut_star);
   |  1
--------
 a |  1
 b |  1
Initial state:   [ 1 ]
Accepting state: [ 1 ]

gap> r_aut_star:=AutomatonToRatExp ( aut_star );
(aa*bUb)(aa*bUb)*(aa*U@)Uaa*U@
gap> r_daut_star:=AutomatonToRatExp ( daut_star );
(aUb)*


Is something wrong with regular expression for nondet automaton?

Could someone please point out where the error is?


Sincerely,
Nikolay Krayinyukov