A strategy profile of a normal form game is proper if and only if it is quas-perfect in every extensive form (with that normal form). Thus, properness requires optimality along a sequency of supporting trembles, while sequentiality only requires optimality in the limit.

Islamic banking is a growing phenomenon which came into existence to satisfy the financial needs of devout Muslims who observe the prohibition of interest-based transactions. Many economists have studied the macroeconomic properties of this institution in the framework of an isolated and ideal...