“…Some examples are the extension of these solutions [9,10], code verification [11,12], rigorous construction of smooth solutions [13,14], etc. On the other hand, recent results in singularity formation in the Euler equation, but out of Guderley problem, are [15][16][17][18][19][20][21]. See also [22][23][24] and references therein for stabilization of relativistic fluids.…”