DAYTON - After 54 holes of the PGA Tour Qualifying tournament at Dayton Valley Golf Club, the only certainty is that three players are tied for the top spot on the leaderboard. The battle is on in the final round to determine the low 19 scores and ties that will move on in the qualifying process.Nathan Tyler (Tucson, Ariz.), Nick Delio (Valencia, Calif.) and Gregor Main (Danville, Calif.) each shot 6-under rounds of 66 to tie for the top spot after 54-holes at 10-under 206. All three were in a similar position after 54-holes last year and each moved on …