--- a/progs/defs.rec	Mon Nov 24 00:11:31 2014 +0000
+++ b/progs/defs.rec	Mon Nov 24 00:42:04 2014 +0000
@@ -65,12 +65,12 @@
 //fib(20)
 //(write(fact(5)) ; fact(6))
 //(write(1) ; 2)
-//ack(2, 3)
+ack(3, 12)   // for tail-rec test
 //stack_test(0)
 //(write (div(11, 3)); rem(11, 3))
 //gcd(54, 24)
 //is_prime(2)
-primes(1000000)
+//primes(1000000)
 //collatz(5000)
 //facT(6, 1)