Next, consider a curved tunnel of total length "A", parameterized by "s" varying from 0 to "A". Let "W(s)" be the variable width of the tunnel. The tunnel can be approximated as a sequence of "N" straight tunnels, numbered 1 through "N", each located at "si" where "i" = 1 to "N", and each of length "s""i"+1 − "s""i" and of width "W"("s""i"). We can let "N" grow arbitrarily large, making the length of successive straight tunnels become infinitesimal. The total time to navigative through the curved tunnel is