src/HOL/Real/RealDef.thy
author paulson
Fri Jul 23 17:29:12 1999 +0200 (1999-07-23)
changeset 7077 60b098bb8b8a
parent 5787 4e5c74b7cd9e
child 7127 48e235179ffb
permissions -rw-r--r--
heavily revised by Jacques: coercions have alphabetic names;
exponentiation is available, etc.
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(*  Title       : Real/RealDef.thy
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    Author      : Jacques D. Fleuriot
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    Copyright   : 1998  University of Cambridge
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    Description : The reals
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*) 
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RealDef = PReal +
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constdefs
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  realrel   ::  "((preal * preal) * (preal * preal)) set"
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  "realrel == {p. ? x1 y1 x2 y2. p = ((x1,y1),(x2,y2)) & x1+y2 = x2+y1}" 
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typedef real = "{x::(preal*preal).True}/realrel"          (Equiv.quotient_def)
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instance
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   real  :: {ord, plus, times, minus}
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consts 
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  "0r"       :: real               ("0r")   
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  "1r"       :: real               ("1r")  
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defs
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  real_zero_def  
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     "0r == Abs_real(realrel^^{(preal_of_prat(prat_of_pnat 1p),
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                                preal_of_prat(prat_of_pnat 1p))})"
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  real_one_def   
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     "1r == Abs_real(realrel^^{(preal_of_prat(prat_of_pnat 1p) + 
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            preal_of_prat(prat_of_pnat 1p),preal_of_prat(prat_of_pnat 1p))})"
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  real_minus_def
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    "- R ==  Abs_real(UN (x,y):Rep_real(R). realrel^^{(y,x)})"
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  real_diff_def "x - y == x + -(y::real)"
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constdefs
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  real_of_preal :: preal => real            
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  "real_of_preal m     ==
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           Abs_real(realrel^^{(m+preal_of_prat(prat_of_pnat 1p),
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                               preal_of_prat(prat_of_pnat 1p))})"
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  rinv       :: real => real
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  "rinv(R)   == (@S. R ~= 0r & S*R = 1r)"
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  real_of_posnat :: nat => real             
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  "real_of_posnat n == real_of_preal(preal_of_prat(prat_of_pnat(pnat_of_nat n)))"
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  real_of_nat :: nat => real          
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  "real_of_nat n    == real_of_posnat n + -1r"
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defs
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  real_add_def  
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  "P + Q == Abs_real(UN p1:Rep_real(P). UN p2:Rep_real(Q).
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                split(%x1 y1. split(%x2 y2. realrel^^{(x1+x2, y1+y2)}) p2) p1)"
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  real_mult_def  
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  "P * Q == Abs_real(UN p1:Rep_real(P). UN p2:Rep_real(Q).
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                split(%x1 y1. split(%x2 y2. realrel^^{(x1*x2+y1*y2,x1*y2+x2*y1)}) p2) p1)"
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  real_less_def
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  "P < Q == EX x1 y1 x2 y2. x1 + y2 < x2 + y1 & 
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                                   (x1,y1):Rep_real(P) &
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                                   (x2,y2):Rep_real(Q)" 
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  real_le_def
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  "P <= (Q::real) == ~(Q < P)"
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end