sirclueless

    C1 --- C2 --- C3
     \      \      \
      T1     T2     T3
       \      \      \
        F1 - - F2 - - F3

    C1 --- C2'--- C3
     \      \      \
      T1     T2'    T3
       \      \      \
        F1 - - \  - - F3
                \
                 F2'

                    --> solve the problem
                  /
    see a problem
                  \
                    --> exploit the problem