With just under 4 weeks to go before the mayoral election, Mayor Bloomberg and City Comptroller William Thompson will march in the Fifth Avenue Columbus Day parade today. And tomorrow is their first debate—some veterans have suggestions (Mark Green to Thompson: ""Don't try for a knockout, because it can't happen"). Thompson skipped two parades yesterday (Bloomberg was at the Bronx Columbus Day Parade and the Hispanic Day Parade in Manhattan), apparently to prepare for the debate.