Before revision:  Several different payment schemeshave been considered. In "{\em first-price " bidding , only the higher bidder pays his bid , while in "{\em all-pay " bidding, both players pay their bids.
After revision:  The bidding mechanisms differ in their payment schemes. Bidding games were largely studied with variants of{\em first-price " bidding , only the higher bidder pays his bid , while in "{\em all-pay " bidding, both players pay their bids.