https://github.com/EasyCrypt/easycrypt
Revision 9ae0786a74ba0aebd9990eb85948bcbdc2e4c3dd authored by Pierre-Yves Strub on 23 April 2018, 13:55:19 UTC, committed by Pierre-Yves Strub on 23 April 2018, 14:06:48 UTC
This revert pattern revert a local-binding as a let-in construct. [closes #17291]
1 parent a18abdf
Tip revision: 9ae0786a74ba0aebd9990eb85948bcbdc2e4c3dd authored by Pierre-Yves Strub on 23 April 2018, 13:55:19 UTC
New revert pattern: `@x`
New revert pattern: `@x`
Tip revision: 9ae0786
WhileSampling.ec
require import Real Distr.
type t.
op sample: t distr.
axiom sample_ll: is_lossless sample.
op test: t -> bool.
axiom pr_ntest: 0%r < mu sample (predC test).
module Sample = {
proc sample () : t = {
var r : t;
r <$ sample;
while (test r) {
r <$ sample;
}
return r;
}
}.
lemma Sample_lossless: islossless Sample.sample.
proof.
proc; seq 1: true=> //.
+ by auto=> />; exact/sample_ll.
while true (if test r then 1 else 0) 1 (mu sample (predC test))=> //.
+ by move=> _ r; case: (test r).
+ move=> ih; seq 1: true=> //.
by auto; rewrite sample_ll.
+ by auto; rewrite sample_ll.
rewrite pr_ntest=> /= z; conseq (: true ==> !test r).
+ smt().
by rnd; auto=> />.
qed.
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