Melvin Turpin and Dirk Minniefield led a second-half rally that gave 12th-ranked Kentucky a 12-point lead as the wildcats defeated Ohio University, 57-40, in a second round of the NCAA Mideast Regional tournament today.

In the second game, Alvin Robertson scored 26 points and had six steals as ninth-ranked Arkansas came back after losing a 10-point second-half lead to beat Purdue, 78-68.

The Wildcats ended a three-game NCAA losing streak in advancing to next week's regional semifinals at Knoxville, Tenn., against the winner of Sunday's Indiana-Oklahoma game. Arkansas will play the winner of Sunday's Louisville-Tennessee game.

Minniefield led Kentucky (22-7) with 16 points and Turpin had 14.

Ohio, the Mid-American Conference tournament champion, used a slow tempo to stay with the heavily favored Wildcats most of the game. The Wildcats were leading, 27-23 with 13:50 to play when they went on an 11-3 run.

Turpin had five points and Minniefield four; Minniefield also made a lob pass that freshman Kenny Walker laid in for the other basket.

Ohio (23-9) could not come within eight the rest of the game. Kentucy never led by more than 12 until scoring the final eight points in the last minute.

Of the wildcats' sluggish start, Coach Joe B. Hall called it "our typical tournament-opening jitters."

He continued: "I'm glad we got it out of the way and were successful. I hope we never play this way again."

"It's good to get this one under our belt," said Minniefield. "It should help our confidence. It will make us looser next week."

John Devereaux, who fouled out in the final minute, led the Bobcats with nine points. Freshman Robert Tatum, who made the 15-footer at the buzzer Thursday night to beat Illinois State, scored eight.

Coach Danny Nee, who led Ohio to a school record for victories this season, said his team "did the things we wanted to go, but I think there were too many Wildcats out there."

Arkansas (26-3) appeared to have a comfortable lead after its pressing defense helped the Razorbacks take a 41-31 lead with 17:34 to play.But Purdue (21-9) cut the lead to 48-47 as Jim Rowinski and Jim Bullock each scored six points. The Boilermakers took their first lead since the opening minutes on two free throws by Steve Reid that made it 49-48 with 10 minutes to play.

The Boilermakers led, 53-48, on a layup by Greg Eifert and two more free throws by Reid. Arkansas regained the lead at 59-57 on a run led by Darrell Walker (22 points) and Robertson.