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(* Title: HOL/prod
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ID: $Id$
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Author: Lawrence C Paulson, Cambridge University Computer Laboratory
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Copyright 1991 University of Cambridge
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For prod.thy. Ordered Pairs, the Cartesian product type, the unit type
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*)
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open Prod;
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(*This counts as a non-emptiness result for admitting 'a * 'b as a type*)
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goalw Prod.thy [Prod_def] "Pair_Rep(a,b) : Prod";
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by (EVERY1 [rtac CollectI, rtac exI, rtac exI, rtac refl]);
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val ProdI = result();
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val [major] = goalw Prod.thy [Pair_Rep_def]
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"Pair_Rep(a, b) = Pair_Rep(a',b') ==> a=a' & b=b'";
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by (EVERY1 [rtac (major RS fun_cong RS fun_cong RS subst),
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rtac conjI, rtac refl, rtac refl]);
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val Pair_Rep_inject = result();
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goal Prod.thy "inj_onto(Abs_Prod,Prod)";
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by (rtac inj_onto_inverseI 1);
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by (etac Abs_Prod_inverse 1);
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val inj_onto_Abs_Prod = result();
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val prems = goalw Prod.thy [Pair_def]
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"[| <a, b> = <a',b'>; [| a=a'; b=b' |] ==> R |] ==> R";
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by (rtac (inj_onto_Abs_Prod RS inj_ontoD RS Pair_Rep_inject RS conjE) 1);
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by (REPEAT (ares_tac (prems@[ProdI]) 1));
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val Pair_inject = result();
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goal Prod.thy "(<a,b> = <a',b'>) = (a=a' & b=b')";
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by (fast_tac (set_cs addIs [Pair_inject]) 1);
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val Pair_eq = result();
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goalw Prod.thy [fst_def] "fst(<a,b>) = a";
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by (fast_tac (set_cs addIs [select_equality] addSEs [Pair_inject]) 1);
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val fst_conv = result();
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goalw Prod.thy [snd_def] "snd(<a,b>) = b";
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by (fast_tac (set_cs addIs [select_equality] addSEs [Pair_inject]) 1);
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val snd_conv = result();
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goalw Prod.thy [Pair_def] "? x y. p = <x,y>";
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by (rtac (rewrite_rule [Prod_def] Rep_Prod RS CollectE) 1);
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by (EVERY1[etac exE, etac exE, rtac exI, rtac exI,
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rtac (Rep_Prod_inverse RS sym RS trans), etac arg_cong]);
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val PairE_lemma = result();
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val [prem] = goal Prod.thy "[| !!x y. p = <x,y> ==> Q |] ==> Q";
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by (rtac (PairE_lemma RS exE) 1);
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by (REPEAT (eresolve_tac [prem,exE] 1));
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val PairE = result();
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goalw Prod.thy [split_def] "split(<a,b>, c) = c(a,b)";
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by (sstac [fst_conv, snd_conv] 1);
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by (rtac refl 1);
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val split = result();
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(*FIXME: split's congruence rule should only simplifies the pair*)
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val pair_ss = set_ss addsimps [fst_conv, snd_conv, split];
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goal Prod.thy "p = <fst(p),snd(p)>";
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by (res_inst_tac [("p","p")] PairE 1);
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by(asm_simp_tac pair_ss 1);
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val surjective_pairing = result();
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goal Prod.thy "p = split(p, %x y.<x,y>)";
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by (res_inst_tac [("p","p")] PairE 1);
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by(asm_simp_tac pair_ss 1);
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val surjective_pairing2 = result();
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(** split used as a logical connective, with result type bool **)
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val prems = goal Prod.thy "c(a,b) ==> split(<a,b>, c)";
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by (stac split 1);
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by (resolve_tac prems 1);
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val splitI = result();
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val prems = goalw Prod.thy [split_def]
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"[| split(p,c); !!x y. [| p = <x,y>; c(x,y) |] ==> Q |] ==> Q";
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by (REPEAT (resolve_tac (prems@[surjective_pairing]) 1));
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val splitE = result();
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goal Prod.thy "R(split(p,c)) = (! x y. p = <x,y> --> R(c(x,y)))";
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by (stac surjective_pairing 1);
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by (stac split 1);
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by (fast_tac (HOL_cs addSEs [Pair_inject]) 1);
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val expand_split = result();
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(*** prod_fun -- action of the product functor upon functions ***)
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goalw Prod.thy [prod_fun_def] "prod_fun(f,g,<a,b>) = <f(a),g(b)>";
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by (rtac split 1);
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val prod_fun = result();
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goal Prod.thy
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"prod_fun(f1 o f2, g1 o g2) = (prod_fun(f1,g1) o prod_fun(f2,g2))";
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by (rtac ext 1);
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by (res_inst_tac [("p","x")] PairE 1);
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by(asm_simp_tac (pair_ss addsimps [prod_fun,o_def]) 1);
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val prod_fun_compose = result();
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goal Prod.thy "prod_fun(%x.x, %y.y) = (%z.z)";
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by (rtac ext 1);
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by (res_inst_tac [("p","z")] PairE 1);
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by(asm_simp_tac (pair_ss addsimps [prod_fun]) 1);
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val prod_fun_ident = result();
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val prems = goal Prod.thy "<a,b>:r ==> <f(a),g(b)> : prod_fun(f,g)``r";
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by (rtac image_eqI 1);
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by (rtac (prod_fun RS sym) 1);
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by (resolve_tac prems 1);
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val prod_fun_imageI = result();
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val major::prems = goal Prod.thy
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"[| c: prod_fun(f,g)``r; !!x y. [| c=<f(x),g(y)>; <x,y>:r |] ==> P \
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\ |] ==> P";
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by (rtac (major RS imageE) 1);
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by (res_inst_tac [("p","x")] PairE 1);
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by (resolve_tac prems 1);
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by (fast_tac HOL_cs 2);
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by (fast_tac (HOL_cs addIs [prod_fun]) 1);
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val prod_fun_imageE = result();
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(*** Disjoint union of a family of sets - Sigma ***)
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val SigmaI = prove_goalw Prod.thy [Sigma_def]
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"[| a:A; b:B(a) |] ==> <a,b> : Sigma(A,B)"
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(fn prems=> [ (REPEAT (resolve_tac (prems@[singletonI,UN_I]) 1)) ]);
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(*The general elimination rule*)
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val SigmaE = prove_goalw Prod.thy [Sigma_def]
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"[| c: Sigma(A,B); \
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\ !!x y.[| x:A; y:B(x); c=<x,y> |] ==> P \
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\ |] ==> P"
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(fn major::prems=>
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[ (cut_facts_tac [major] 1),
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(REPEAT (eresolve_tac [UN_E, singletonE] 1 ORELSE ares_tac prems 1)) ]);
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(** Elimination of <a,b>:A*B -- introduces no eigenvariables **)
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val SigmaD1 = prove_goal Prod.thy "<a,b> : Sigma(A,B) ==> a : A"
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(fn [major]=>
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[ (rtac (major RS SigmaE) 1),
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(REPEAT (eresolve_tac [asm_rl,Pair_inject,ssubst] 1)) ]);
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val SigmaD2 = prove_goal Prod.thy "<a,b> : Sigma(A,B) ==> b : B(a)"
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(fn [major]=>
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[ (rtac (major RS SigmaE) 1),
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(REPEAT (eresolve_tac [asm_rl,Pair_inject,ssubst] 1)) ]);
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val SigmaE2 = prove_goal Prod.thy
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"[| <a,b> : Sigma(A,B); \
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\ [| a:A; b:B(a) |] ==> P \
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\ |] ==> P"
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(fn [major,minor]=>
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[ (rtac minor 1),
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(rtac (major RS SigmaD1) 1),
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(rtac (major RS SigmaD2) 1) ]);
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(*** Domain of a relation ***)
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val prems = goalw Prod.thy [image_def] "<a,b> : r ==> a : fst``r";
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by (rtac CollectI 1);
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by (rtac bexI 1);
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by (rtac (fst_conv RS sym) 1);
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by (resolve_tac prems 1);
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val fst_imageI = result();
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val major::prems = goal Prod.thy
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"[| a : fst``r; !!y.[| <a,y> : r |] ==> P |] ==> P";
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by (rtac (major RS imageE) 1);
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by (resolve_tac prems 1);
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by (etac ssubst 1);
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by (rtac (surjective_pairing RS subst) 1);
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by (assume_tac 1);
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val fst_imageE = result();
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(*** Range of a relation ***)
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val prems = goalw Prod.thy [image_def] "<a,b> : r ==> b : snd``r";
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by (rtac CollectI 1);
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by (rtac bexI 1);
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by (rtac (snd_conv RS sym) 1);
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by (resolve_tac prems 1);
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val snd_imageI = result();
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val major::prems = goal Prod.thy
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"[| a : snd``r; !!y.[| <y,a> : r |] ==> P |] ==> P";
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by (rtac (major RS imageE) 1);
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by (resolve_tac prems 1);
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by (etac ssubst 1);
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by (rtac (surjective_pairing RS subst) 1);
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by (assume_tac 1);
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val snd_imageE = result();
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(** Exhaustion rule for unit -- a degenerate form of induction **)
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goalw Prod.thy [Unity_def]
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"u = Unity";
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by (stac (rewrite_rule [Unit_def] Rep_Unit RS CollectD RS sym) 1);
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by (rtac (Rep_Unit_inverse RS sym) 1);
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val unit_eq = result();
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