Graph-regex.md

 # Query format
 
+We have chosen to implement a graph topology search engine in regex form.
+
 ## Graph sequence separation
 
+We decide to decompose a graph to series to applies classic regex to all the series. this decomposition of a graph into multiple sub serial graph use the concept of **common node** noted `node#{n}` where n is use to distinguished **common node** with the same node type .These type of node are use to store were the original graph was cut.
+
+for ex :
+
+```mermaid
+
+	graph TD;
+	classDef ref fill:#f96
+	
+	A0 --> B0 & C0
+	B0 --> D0
+	C0 --> D0
+	
+```
+
+After decomposition :
+
+```mermaid
+
+	graph TD;
+	classDef ref fill:#f96
+	
+	A0 --> B0 & C0
+	B0 --> D0
+	C0 --> D0
+	
+```
+
 ## Regex keys
 
 # FSM generation