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(*  Title:      Cube/cube.thy
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    ID:         $Id$
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    Author:     Tobias Nipkow
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    Copyright   1993  University of Cambridge
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Barendregt's Lambda-Cube
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*)
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Cube = Pure +
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types
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  term, context, typing 0
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arities
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  term :: logic
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consts
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  Abs, Prod     :: "[term, term => term] => term"
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  Trueprop      :: "[context, typing] => prop"          ("(_/ |- _)")
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  Trueprop1     :: "typing => prop"                     ("(_)")
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  MT_context    :: "context"                            ("")
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  ""            :: "id => context"                      ("_ ")
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  ""            :: "var => context"                     ("_ ")
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  Context       :: "[typing, context] => context"       ("_ _")
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  star          :: "term"                               ("*")
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  box           :: "term"                               ("[]")
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  "^"           :: "[term, term] => term"               (infixl 20)
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21
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  Lam           :: "[idt, term, term] => term"          ("(3Lam _:_./ _)" [0, 0, 0] 10)
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  Pi            :: "[idt, term, term] => term"          ("(3Pi _:_./ _)" [0, 0] 10)
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  "->"          :: "[term, term] => term"               (infixr 10)
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  Has_type      :: "[term, term] => typing"             ("(_:/ _)" [0, 0] 5)
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translations
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  (prop) "x:X"  == (prop) "|- x:X"
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  "Lam x:A. B"  == "Abs(A, %x. B)"
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  "Pi x:A. B"   => "Prod(A, %x. B)"
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  "A -> B"      => "Prod(A, _K(B))"
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rules
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  s_b           "*: []"
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  strip_s       "[| A:*;  a:A ==> G |- x:X |] ==> a:A G |- x:X"
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  strip_b       "[| A:[]; a:A ==> G |- x:X |] ==> a:A G |- x:X"
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  app           "[| F:Prod(A, B); C:A |] ==> F^C: B(C)"
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  pi_ss         "[| A:*; !!x. x:A ==> B(x):* |] ==> Prod(A, B):*"
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  lam_ss        "[| A:*; !!x. x:A ==> f(x):B(x); !!x. x:A ==> B(x):* |] \
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\                   ==> Abs(A, f) : Prod(A, B)"
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  beta          "Abs(A, f)^a == f(a)"
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end
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ML
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val print_translation = [("Prod", dependent_tr' ("Pi", "op ->"))];
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