let M be non empty calculating_type halting Moore-SM_Final of [:REAL ,REAL :], succ REAL ; ( the carrier of M = succ REAL & the FinalS of M = REAL & the InitS of M = REAL & the OFun of M = id the carrier of M & ( for x, y being Real st ( x > 0 or y > 0 ) holds
the Tran of M . [the InitS of M,[x,y]] = 1 ) & ( for x, y being Real st ( x = 0 or y = 0 ) & x <= 0 & y <= 0 holds
the Tran of M . [the InitS of M,[x,y]] = 0 ) & ( for x, y being Real st x < 0 & y < 0 holds
the Tran of M . [the InitS of M,[x,y]] = - 1 ) implies for x, y being Element of REAL holds Result [x,y],M = max (sgn x),(sgn y) )
assume that
A1:
the carrier of M = succ REAL
and
A2:
the FinalS of M = REAL
and
A3:
the InitS of M = REAL
and
A4:
the OFun of M = id the carrier of M
; ( ex x, y being Real st
( ( x > 0 or y > 0 ) & not the Tran of M . [the InitS of M,[x,y]] = 1 ) or ex x, y being Real st
( ( x = 0 or y = 0 ) & x <= 0 & y <= 0 & not the Tran of M . [the InitS of M,[x,y]] = 0 ) or ex x, y being Real st
( x < 0 & y < 0 & not the Tran of M . [the InitS of M,[x,y]] = - 1 ) or for x, y being Element of REAL holds Result [x,y],M = max (sgn x),(sgn y) )
assume that
A5:
for x, y being Real st ( x > 0 or y > 0 ) holds
the Tran of M . [the InitS of M,[x,y]] = 1
and
A6:
for x, y being Real st ( x = 0 or y = 0 ) & x <= 0 & y <= 0 holds
the Tran of M . [the InitS of M,[x,y]] = 0
and
A7:
for x, y being Real st x < 0 & y < 0 holds
the Tran of M . [the InitS of M,[x,y]] = - 1
; for x, y being Element of REAL holds Result [x,y],M = max (sgn x),(sgn y)
let x, y be Real; Result [x,y],M = max (sgn x),(sgn y)
A8:
max (sgn x),(sgn y) in succ REAL
by XBOOLE_0:def 3;
max (sgn x),(sgn y) is_result_of [x,y],M
by A1, A2, A3, A4, A5, A6, A7, Th26;
hence
Result [x,y],M = max (sgn x),(sgn y)
by A8, Def9; verum