The basic, fair exchange

However much each member exchanges is equal to both parties.  For example:

Bob has 5 hours for sale, and Sue has 12.

Sue buys Bobs for 3 hours and Bob get 5 hours

Bob buys Sues for 7 and Sue get 12

The total amount of time created in this transaction is 5-2 + 12-7 = 8.  Since Sue got more than Bob, she transfers the overage to Bob, also taking a fee for giving a gift such that the amount each received is equal.  The would happen to everyone in an exchange epoch, everyone getting the same amount of time created as everyone else.

This is not the most optimal due to the loss from the exchange of money.

Popularity based

Depending on the number of 'likes' you get from members determines who you exchange with.  Those at the bottom exchange with those who have the most time to offer relative to how much they have to offer and their own popularity.

Balance based

Those with the least amount of balance in their account get the most, those with the most get the least.

Others...

Under construction