Input:   𝐺 𝑘 : The input graph
   𝑐 𝑢 𝑟 𝑁 𝑜 𝑑 𝑒 : The current node to be inspected
Output:   𝑒 𝑥 𝑖 𝑡 𝑁 𝑜 𝑑 𝑒 : The trailer node
1:  𝑥 = 𝐹 𝑖 𝑛 𝑑 𝑀 𝑖 𝑛 𝑖 𝑚 𝑎 𝑙 𝑅 𝑒 𝑔 𝑖 𝑜 𝑛 ( 𝑐 𝑢 𝑟 𝑁 𝑜 𝑑 𝑒 )     // Takes
  care of nested regions
2:  if 𝑥 = 𝑁 𝑈 𝐿 𝐿   then
3:   𝑒 𝑥 𝑖 𝑡 𝑁 𝑜 𝑑 𝑒 = 𝑅 𝑒 𝑑 𝑢 𝑐 𝑒 𝑅 𝑒 𝑔 𝑖 𝑜 𝑛 ( 𝑐 𝑢 𝑟 𝑁 𝑜 𝑑 𝑒 )     // Do
    the composition following composition rules
4:   𝑈 𝑝 𝑑 𝑎 𝑡 𝑒 ( 𝐺 𝑘 )     // Update 𝐺 𝑘 with CCG at 𝑐 𝑢 𝑟 𝑁 𝑜 𝑑 𝑒
5:  else // Indicates a nested region is found
6:   𝑒 𝑥 𝑖 𝑡 𝑁 𝑜 𝑑 𝑒 = 𝑅 𝑒 𝑑 𝑢 𝑐 𝑒 𝑅 𝑒 𝑔 𝑖 𝑜 𝑛 ( 𝑥 )     // 𝑥 is the entry node
7:   𝑈 𝑝 𝑑 𝑎 𝑡 𝑒 ( 𝐺 𝑘 )
8:   𝑒 𝑥 𝑖 𝑡 𝑁 𝑜 𝑑 𝑒    =    𝐶 𝑜 𝑚 𝑝 𝑜 𝑠 𝑒 𝑅 𝑒 𝑔 𝑖 𝑜 𝑛 ( 𝐺 𝑘 , 𝑐 𝑢 𝑟 𝑁 𝑜 𝑑 𝑒 )
        // recursively repeat the composition
9:  end if
10:  return  𝑒 𝑥 𝑖 𝑡 𝑁 𝑜 𝑑 𝑒
Function ComposeRegion(G, RegionFound)
Procedure 4: Function ComposeRegion.