From 1ce05fa9fe76861c6fab7ccbb0e94b0be92a951e Mon Sep 17 00:00:00 2001
From: phawaderamchandra <prb@iitdh.ac.in>
Date: Thu, 19 Oct 2023 11:39:26 +0530
Subject: [PATCH] class 27, Oct 19,2023

---
 class_27_19102023/summary.txt | 8 ++++++++
 1 file changed, 8 insertions(+)
 create mode 100644 class_27_19102023/summary.txt

diff --git a/class_27_19102023/summary.txt b/class_27_19102023/summary.txt
new file mode 100644
index 0000000..fe651b5
--- /dev/null
+++ b/class_27_19102023/summary.txt
@@ -0,0 +1,8 @@
+Applications of CT
+
+-- class of structures which has finitely many elements is not
+definable in FO with equality.
+
+-- class of graphs G=(V,E,a,b) where there is a path from a to b is
+not definable in FO with signature <{a,b},{},{R(,)}> 
+