The Coppersmith-Tetali-Winkler Identity for Mechanical Systems
  Using a mixture of linear algebra and statics, we derive what can be viewed as a slight generalization of the Coppersmith-Tetali-Winkler Identity $H(i,j)+H(j,k)+H(k,i)=H(j,i)+H(k,j)+H(i,k)$ for hitting times of a random walk. 
Andrei Kotlov