We propose a new definition of cosmic voids based on methods of Lagrangian orbit reconstruction as well as an algorithm to find them in actual data called DIVA .
Our technique is intended to yield results which can be modeled sufficiently accurately to create a new probe of precision cosmology .
We then develop an analytical model of the ellipticity of voids found by our method based on Zel ’ dovich approximation .
We measure in N -body simulation that this model is precise at the \sim 0.1 % level for the mean ellipticity of voids of size greater than \sim 4 h ^ { -1 } Mpc .
We estimate that at this scale , we are able to predict the ellipticity with an accuracy of \sigma _ { \varepsilon } \sim 0.02 .
Finally , we compare the distribution of void shapes in N -body simulation for two different equations of state w of the dark energy .
We conclude that our method is far more accurate than Eulerian methods and is therefore promising as a precision probe of dark energy phenomenology .