let OAlph, IAlph be non empty set ; :: thesis: for tfsm being non empty Mealy-FSM of IAlph,OAlph
for qa, qb being State of tfsm holds
( qa,qb -are_equivalent iff for s being Element of IAlph holds
( the OFun of tfsm . [qa,s] = the OFun of tfsm . [qb,s] & the Tran of tfsm . [qa,s],the Tran of tfsm . [qb,s] -are_equivalent ) )

let tfsm be non empty Mealy-FSM of IAlph,OAlph; :: thesis: for qa, qb being State of tfsm holds
( qa,qb -are_equivalent iff for s being Element of IAlph holds
( the OFun of tfsm . [qa,s] = the OFun of tfsm . [qb,s] & the Tran of tfsm . [qa,s],the Tran of tfsm . [qb,s] -are_equivalent ) )

let qa, qb be State of tfsm; :: thesis: ( qa,qb -are_equivalent iff for s being Element of IAlph holds
( the OFun of tfsm . [qa,s] = the OFun of tfsm . [qb,s] & the Tran of tfsm . [qa,s],the Tran of tfsm . [qb,s] -are_equivalent ) )

set OF = the OFun of tfsm;
hereby :: thesis: ( ( for s being Element of IAlph holds
( the OFun of tfsm . [qa,s] = the OFun of tfsm . [qb,s] & the Tran of tfsm . [qa,s],the Tran of tfsm . [qb,s] -are_equivalent ) ) implies qa,qb -are_equivalent )
assume A1: qa,qb -are_equivalent ; :: thesis: for s being Element of IAlph holds
( the OFun of tfsm . [qa,s] = the OFun of tfsm . [qb,s] & the Tran of tfsm . [qa,s],the Tran of tfsm . [qb,s] -are_equivalent )

let s be Element of IAlph; :: thesis: ( the OFun of tfsm . [qa,s] = the OFun of tfsm . [qb,s] & the Tran of tfsm . [qa,s],the Tran of tfsm . [qb,s] -are_equivalent )
set qa9 = the Tran of tfsm . [qa,s];
set qb9 = the Tran of tfsm . [qb,s];
len <*s*> = 1 by FINSEQ_1:57;
then A2: 1 in dom <*s*> by FINSEQ_3:27;
thus A3: the OFun of tfsm . [qa,s] = the OFun of tfsm . [((qa,<*s*> -admissible ) . 1),s] by Def2
.= the OFun of tfsm . [((qa,<*s*> -admissible ) . 1),(<*s*> . 1)] by FINSEQ_1:57
.= (qa,<*s*> -response ) . 1 by A2, Def6
.= (qb,<*s*> -response ) . 1 by A1, Def10
.= the OFun of tfsm . [((qb,<*s*> -admissible ) . 1),(<*s*> . 1)] by A2, Def6
.= the OFun of tfsm . [((qb,<*s*> -admissible ) . 1),s] by FINSEQ_1:57
.= the OFun of tfsm . [qb,s] by Def2 ; :: thesis: the Tran of tfsm . [qa,s],the Tran of tfsm . [qb,s] -are_equivalent
now
let w be FinSequence of IAlph; :: thesis: (the Tran of tfsm . [qa,s]),w -response = (the Tran of tfsm . [qb,s]),w -response
A4: ( qa,(<*s*> ^ w) -response = <*(the OFun of tfsm . [qa,s])*> ^ ((the Tran of tfsm . [qa,s]),w -response ) & qb,(<*s*> ^ w) -response = <*(the OFun of tfsm . [qb,s])*> ^ ((the Tran of tfsm . [qb,s]),w -response ) ) by Th35;
qa,(<*s*> ^ w) -response = qb,(<*s*> ^ w) -response by A1, Def10;
hence (the Tran of tfsm . [qa,s]),w -response = (the Tran of tfsm . [qb,s]),w -response by A3, A4, FINSEQ_1:46; :: thesis: verum
end;
hence the Tran of tfsm . [qa,s],the Tran of tfsm . [qb,s] -are_equivalent by Def10; :: thesis: verum
end;
assume A5: for s being Element of IAlph holds
( the OFun of tfsm . [qa,s] = the OFun of tfsm . [qb,s] & the Tran of tfsm . [qa,s],the Tran of tfsm . [qb,s] -are_equivalent ) ; :: thesis: qa,qb -are_equivalent
let w be FinSequence of IAlph; :: according to FSM_1:def 10 :: thesis: qa,w -response = qb,w -response
per cases ( w = <*> IAlph or w <> {} ) ;
suppose A6: w = <*> IAlph ; :: thesis: qa,w -response = qb,w -response
hence qa,w -response = <*> OAlph by Th24
.= qb,w -response by A6, Th24 ;
:: thesis: verum
end;
suppose w <> {} ; :: thesis: qa,w -response = qb,w -response
then consider s being Element of IAlph, wt being FinSequence of IAlph such that
s = w . 1 and
A7: w = <*s*> ^ wt by FINSEQ_3:111;
set bsresp = the OFun of tfsm . [qb,s];
set asresp = the OFun of tfsm . [qa,s];
set qb9 = the Tran of tfsm . [qb,s];
set qa9 = the Tran of tfsm . [qa,s];
the Tran of tfsm . [qa,s],the Tran of tfsm . [qb,s] -are_equivalent by A5;
then A8: (the Tran of tfsm . [qa,s]),wt -response = (the Tran of tfsm . [qb,s]),wt -response by Def10;
thus qa,w -response = <*(the OFun of tfsm . [qa,s])*> ^ ((the Tran of tfsm . [qa,s]),wt -response ) by A7, Th35
.= <*(the OFun of tfsm . [qb,s])*> ^ ((the Tran of tfsm . [qb,s]),wt -response ) by A5, A8
.= qb,w -response by A7, Th35 ; :: thesis: verum
end;
end;