National Basketball Association star Julius Erving finally got his college degree, to the delight of his mother and thousands of other graduating students at the University of Massachusetts commencement yesterday in Amherst, Mass.

"I hope Dr. Erving does not decide to run for governor," Gov. Michael Dukakis told the crowd of 25,000 after one of several ovations for the Phildelphia 76ers forward. "If he does, I'm through."

With the degree in leadership and administration, Erving, 36, fulfilled a promise he made 16 years ago when he dropped out of the university with just one year to go to begin his professional basketball career with the American Basketball Association.

"I don't need the degree to go forward with the present endeavors with which I am involved, but I feel personally that I needed to fulfill a commitment I started in 1968 and to fulfill a promise I made to my mother," said the 76ers' captain.

Erving was among 4,324 students to receive undergraduate degrees at Massachusetts and one of a half-dozen worthies to receive an honorary doctor of law degree.

Erving completed his degree work over the last year and a half through the University Without Walls program, an individualized degree program with a curriculum designed for adults who are unable to attend traditional college classes because of work or family commitments.

He said the degree will help him "speak with more credibility to young people in general and to my own children in particular." . . .

Detroit Pistons all-star guard Isiah Thomas will undergo two operations in the next eight days to repair a chronically sore joint in his left thumb.

Pins will be surgically placed in his thumb Wednesday and bone fusion surgery will be performed the following Monday on the middle of the three joints in the thumb.

"It shouldn't affect the way he plays basketball," said Dr. Eugene Horrell, who will perform the operations. "He should be able to hold or control a basketball as well as ever, maybe even a little bit better than before."

Thomas said the thumb had been chronically sore for "about as long as I can remember" because of the beating it has taken during his basketball career. But he said the pain worsened sharply after a March 7 game against the New Jersey Nets, and he now "can't control" the thumb.

HORSE RACING

Retired jockey Eddie Arcaro was "coming along nicely" in intensive care at a Miami hospital where he underwent open-heart surgery, his doctor said.

Dr. Malcolm Dorman said the 70-year-old, five-time Kentucky Derby winner would remain in intensive care a few days and could expect a 10-day to two-week stay at Miami Heart Institute. "It's hard to say because of the extensive surgery he had, but so far things are really going very well," Dorman said. "He's coming along nicely. We're pleased."

Arcaro retired in 1962 after a 31-year career in which he won 4,779 races with earnings of $30,039,543. He won the Kentucky Derby five times, a mark later equaled by Bill Hartack. His record of six victories each at the Preakness and Belmont Stakes remains intact.

COLLEGES

Jose Trujillo's infield single in the 10th inning lifted the University of Miami (Fla.) over Georgia Tech, 7-6, advancing the Hurricanes to the finals of the NCAA Atlantic Regional double-elimination baseball tournament.

Georgia Tech later came back to beat Alabama, 9-3, eliminating the Crimson Tide and advancing to the final against Miami.

Miami, the defending national champion, can earn its third straight trip to the College World Series with one more victory. Georgia Tech must beat Miami twice today to claim the regional title.

BASEBALL

Turner Gill, the former two-sport star at Nebraska who had to give up a pro football career because of head injuries, was signed to a minor league baseball contract by the Cleveland Indians.

Gill, 23, was the starting quarterback with the Montreal Concordes of the Canadian Football League the last two years. Doctors advised him to quit football after he suffered three concussions last season. Gill, a shortstop, was assigned to Waterloo (Iowa) of the Class-A Midwest League.

"I had some concussions during the past season and the doctors recommended I do not play football," Gill said. "I am still fairly young and I figure I will give baseball a shot."

Gill played one year of baseball at Nebraska and was drafted in the second round of the June 1980 draft by the Chicago White Sox. In 1983, he was an 18th-round selection of the New York Yankees.

TRACK AND FIELD

Olympic silver medalist Jackie Joyner of the United States scored a year's best 6,841 points in the heptathlon to win the two-day event at an international track meet in Goetzis, Austria. Joyner won three of the events -- the 100-meter hurdles (13.09 seconds), the shot put (47 feet 1 inch) and the 200 meters (23.63).

Anke Behmer of East Germany was second with 6,530 points and Sabine Braun of West Germany finished third with 6,418.

MODERN PENTATHLON

Rob Stull of Damascus, Md., won the fencing competition on the second day of the Modern Pentathlon National Championships in San Antonio and moved into first place after two events with 2,080 points. Four-time national champion Mike Burley is in second place with 1,940.