( 2π2 )* . (2π1.2π1,+.(id.2π1.2π2,id.2π2.2π2)o.(2π1.2π1,(2π2.2π1,2π2.2π2)o)o)o // . distl . (id,++.(b_allvec[0]o,id)o)o . id . id . id