initial commit

projects/task3/alpha_equiv.c

@@ -0,0 +1,39 @@
+#include "ast.h"
+
+bool alpha_equiv(term *t1, term *t2)
+{
+    if (t1 == (void*) 0 || t2 == (void*) 0)
+        return false;
+    if (t1->type != t2->type)
+        return false;
+    switch (t1->type){
+        case Var: {
+            return strcmp(t1->content.Var, t2->content.Var) == 0;
+        }
+        case Const: {
+            if (t1->content.Const.type != t2->content.Const.type)
+                return false;
+            if (t1->content.Const.type == Num){
+                return t1->content.Const.content == t2->content.Const.content;
+            }
+            return true;
+        }
+        case Apply: {
+            return alpha_equiv(t1->content.Apply.left, t2->content.Apply.left) &&
+                alpha_equiv(t1->content.Apply.right, t2->content.Apply.right);
+        }
+        case Quant: {
+            if (t1->content.Quant.type != t2->content.Quant.type)
+                return false;
+            if (strcmp(t1->content.Quant.var, t2->content.Quant.var) == 0){
+                return alpha_equiv(t1->content.Quant.body, t2->content.Quant.body);
+            }
+            else{
+                term *t21 = subst_var(t1->content.Quant.var, t2->content.Quant.var, copy_term(t2->content.Quant.body));
+                bool result = alpha_equiv(t1->content.Quant.body, t21);
+                free_term(t21);
+                return result;
+            }
+        }
+    }
+}