diff --git a/runtime/src/check.rs b/runtime/src/check.rs
index a9a47f64..1bf44116 100644
--- a/runtime/src/check.rs
+++ b/runtime/src/check.rs
@@ -1,7 +1,58 @@
 use sp_core::H256;
 use sp_std::vec::Vec;
+use sp_std::str::from_utf8;
+use sp_std::collections::btree_set;
 
 pub(crate) fn check_obj(_alg_id: &[u8;16], _obj: &Vec<u8>, _hashes: &Vec<H256>) -> bool {
-	// TODO: additional validation
-	true
+
+    use sp_std::vec;
+    use sp_consensus_poscan::decompress_obj;
+
+	let mut obj = _obj.clone();
+
+	if obj[..4] == vec![b'l', b'z', b's', b's'] {
+		obj = decompress_obj(&obj[4..]);
+	}
+
+	check_simply_connected(&obj)
 }
+
+fn check_simply_connected(obj: &Vec<u8>) -> bool {
+    if let Ok(text) = from_utf8(&obj) {
+        let mut vs_list = btree_set::BTreeSet::new();//::with_capacity(6000);
+        for line in text.lines() {
+            let words: Vec<&str> = line.split_whitespace().collect();
+            if words.len() > 0 {
+                match words[0] {
+                    "f" => {
+                        if words.len() == 4 {
+                            let mut vs = [0,0,0];
+                            for idx in 1..=3 {
+                                let swords: Vec<&str> = words[idx].split("/").collect();
+                                if swords.len() == 3 {
+                                    if let Ok(i) = swords[0].parse() {
+                                        vs[idx-1] = i;
+                                    }
+                                }
+                            }
+                            if vs_list.is_empty()
+                            || vs_list.contains(&vs[0])
+                            || vs_list.contains(&vs[1])
+                            || vs_list.contains(&vs[2]) {
+                                vs_list.insert(vs[0]);
+                                vs_list.insert(vs[1]);
+                                vs_list.insert(vs[2]);
+                            } else {
+                                return false;
+                            }
+                        }
+                    },
+                    _=>{},
+                }
+            }
+        }
+        true
+    } else {
+        false
+    }
+}
\ No newline at end of file
diff --git a/runtime/src/lib.rs b/runtime/src/lib.rs
index f08bd4e9..1dfc2d05 100644
--- a/runtime/src/lib.rs
+++ b/runtime/src/lib.rs
@@ -148,7 +148,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	//   `spec_version`, and `authoring_version` are the same between Wasm and native.
 	// This value is set to 100 to notify Polkadot-JS App (https://polkadot.js.org/apps) to use
 	//   the compatible custom types.
-	spec_version: 123,
+	spec_version: 124,
 	impl_version: 1,
 	apis: RUNTIME_API_VERSIONS,
 	transaction_version: 1,