It is well known that if ${\bf T_2}$ (or $I\Delta_0+\Omega_1$) is finitely axiomatizable, then the Polynomial Hierarchy collapses. > Q. Is there any similar relation between $I\Delta_0$ and Linear Time Hierarchy? **Edit: related question** > Q'. Why standard proof (like corollary 4.39 in chapter V of metamathematics of first-order arithmetic) of > Finite axiomatizability of ${\bf T_2}$ $\Rightarrow$ PH collapse. > does not work for proving > Finite axiomatizability of ${\bf {\bf I}\Delta_0}$ $\Rightarrow$ LiH collapse ? Thanks in advance.