aboutsummaryrefslogtreecommitdiff
path: root/ex
diff options
context:
space:
mode:
Diffstat (limited to 'ex')
-rw-r--r--ex/Synthesis.thy16
1 files changed, 7 insertions, 9 deletions
diff --git a/ex/Synthesis.thy b/ex/Synthesis.thy
index ef6673c..cd5c4e1 100644
--- a/ex/Synthesis.thy
+++ b/ex/Synthesis.thy
@@ -19,9 +19,7 @@ text "
This is also done in \<open>CTT.thy\<close>; there the work is easier as the equality type is extensional, and also the methods are set up a little more nicely.
"
-text "
- First we show that the property we want is well-defined.
-"
+text "First we show that the property we want is well-defined."
lemma pred_welltyped: "\<Sum>pred:\<nat>\<rightarrow>\<nat> . ((pred`0) =\<^sub>\<nat> 0) \<times> (\<Prod>n:\<nat>. (pred`(succ n)) =\<^sub>\<nat> n): U(O)"
by simple
@@ -40,11 +38,11 @@ apply (rule Nat_rules | assumption)+
done
text "
- The above proof finds a candidate, namely \<open>\<^bold>\<lambda>n. ind\<^sub>\<nat> (\<lambda>a b. a) n n\<close>.
+ The above proof finds a candidate, namely \<open>\<^bold>\<lambda>n. ind\<^sub>\<nat> (\<lambda>a b. a) 0 n\<close>.
We prove this has the required type and properties.
"
-definition pred :: Term where "pred \<equiv> \<^bold>\<lambda>n. ind\<^sub>\<nat> (\<lambda>a b. a) n n"
+definition pred :: Term where "pred \<equiv> \<^bold>\<lambda>n. ind\<^sub>\<nat> (\<lambda>a b. a) 0 n"
lemma pred_type: "pred: \<nat> \<rightarrow> \<nat>" unfolding pred_def by simple
@@ -52,7 +50,7 @@ lemma pred_props: "<refl(0), \<^bold>\<lambda>n. refl(n)>: ((pred`0) =\<^sub>\<n
proof (simple lems: pred_type)
have *: "pred`0 \<equiv> 0" unfolding pred_def
proof compute
- show "\<And>n. n: \<nat> \<Longrightarrow> ind\<^sub>\<nat> (\<lambda>a b. a) n n: \<nat>" by simple
+ show "\<And>n. n: \<nat> \<Longrightarrow> ind\<^sub>\<nat> (\<lambda>a b. a) 0 n: \<nat>" by simple
show "ind\<^sub>\<nat> (\<lambda>a b. a) 0 0 \<equiv> 0"
proof (rule Nat_comps)
show "\<nat>: U(O)" ..
@@ -62,10 +60,10 @@ proof (simple lems: pred_type)
show "\<^bold>\<lambda>n. refl(n): \<Prod>n:\<nat>. (pred`(succ(n))) =\<^sub>\<nat> n"
unfolding pred_def proof
- show "\<And>n. n: \<nat> \<Longrightarrow> refl(n): ((\<^bold>\<lambda>n. ind\<^sub>\<nat> (\<lambda>a b. a) n n)`succ(n)) =\<^sub>\<nat> n"
+ show "\<And>n. n: \<nat> \<Longrightarrow> refl(n): ((\<^bold>\<lambda>n. ind\<^sub>\<nat> (\<lambda>a b. a) 0 n)`succ(n)) =\<^sub>\<nat> n"
proof compute
- show "\<And>n. n: \<nat> \<Longrightarrow> ind\<^sub>\<nat> (\<lambda>a b. a) n n: \<nat>" by simple
- show "\<And>n. n: \<nat> \<Longrightarrow> refl(n): ind\<^sub>\<nat> (\<lambda>a b. a) (succ n) (succ n) =\<^sub>\<nat> n"
+ show "\<And>n. n: \<nat> \<Longrightarrow> ind\<^sub>\<nat> (\<lambda>a b. a) 0 n: \<nat>" by simple
+ show "\<And>n. n: \<nat> \<Longrightarrow> refl(n): ind\<^sub>\<nat> (\<lambda>a b. a) 0 (succ n) =\<^sub>\<nat> n"
proof compute
show "\<nat>: U(O)" ..
qed simple