Try to get a fix on this Big East Conference tournament, which begins tonight at Madison Square Garden.

For the past two months, lunacy has been the law of the Big East land. Follow this funky mathematical progression of the regular season and watch the normal, calculating thought process go haywire:

* Top-seeded Boston College twice defeated third-seeded St. John's.

* St. John's twice defeated fourth-seeded Georgetown.

* Georgetown twice defeated fifth-seeded Syracuse.

* Syracuse twice defeated Boston College.

And so we have come full circle. Now, increase the circle's diameter with the fact that second-seeded Villanova has split two games with each of those four teams. And stretch the diameter even further with the fact that sixth-seeded Pittsburgh, king of the Big East upset, has beaten Georgetown, Syracuse and St. John's.

As National Basketball Association scout Marty Blake, a man who has witnessed many a Big East game, says, "In this conference, everybody beats everybody else. So how do you know who will win the tournament?"

Only an elimination game will be played tonight. Last-place Seton Hall (5-22, 1-15) plays eighth-place Providence (12-18, 4-12) for rights to play Boston College at 9 p.m. Thursday is the day the rest of the teams will dive into the cauldron of craziness.

Some in the conference quietly pick Boston College (22-5, 12-4), which tied Villanova and St. John's for first place in the regular season, but won top seeding by virtue of the best record (3-1) in head-to-head competition with these two teams.

After all, BC has won nine of its last 10 games, plays a pressure fullcourt defense that drills fatigue and turnovers into opponents and has the inside-out combination of center John Garris (19.7 points per game, second in the conference) and jump-shooting lefty forward Jay Murphy (17.4 points).

"I think we can win it," said Michael Adams, the Eagles' fidgety and feisty guard, "as long as we can stay away from Syracuse."

Some pick Villanova (21-6, 12-4), which opens against seventh-seeded Connecticut (12-15, 5-11) at 3 p.m. Thursday. These Wildcats seemed so fearsome before suffering a 87-71 collapse against Georgetown Saturday in a game that could have given them their second-straight regular-season title.

"We've played one of the toughest schedules in the country: 27 wars," says Villanova Coach Rollie Massimino. "I would like for the players to have some fun in this (tournament) and build for the NCAA."

It is 6-foot-8, 230-pound senior center John Pinone (17 points per game) who usually mans the bunkers for Villanova, an experienced team that likes to run. If senior guard Stewart Granger can escape some of the inconsistencies of his season, the 'Cats might not only run in this tournament, they might run and hide.

Then again, some quietly pick St. John's (24-4, 12-4), which opens against Pittsburgh (13-14, 6-10) at 1 p.m. Thursday. "Playing in Madison Square Garden is a definite home-court advantage for St. John's," noted Gary Williams, Boston College's first-year coach.

St. John's has the so-smooth jumpers of sophomore Chris Mullin (18.6 points, 57 percent from the field) and the poise of seniors David Russell (16.0 points) and Billy Goodwin (13.4).

There are those who quietly pick Georgetown (21-8, 11-5), the team that won last year's Big East tournament and the NCAA tournament bid that such a victory carries with it. The Hoyas open against Syracuse (19-8, 9-7) Thursday at 7 p.m.

"Anytime you have a Patrick Ewing," says Blake, "you have a chance."

The Hoyas have advanced into the highest level of competence in the past week, first turning aggressive in knocking Villanova flat, then employing a similar rage in the second half to defeat Syracuse, 80-75, Monday night.

Ewing, 7-foot sophomore center, has been magnificent. He had 26 points and 13 rebounds against Syracuse to bump his season averages to 17.4 points and 10.2 rebounds per game.

Even though junior guard Fred Brown, with a strained right knee, continues to be listed as "doubtful" for the tournament, junior Gene Smith has brought a new defensive frenzy and passing touch (12 assists against Syracuse).

Once a team of grand efficiency, Syracuse is in disarray. The Orange are experienced, but have lost two straight (the first, 55-54, at Connecticut) at a time when one more victory might have secured an NCAA bid. Senior forward Tony Bruin has a sprained right ankle and, Syracuse officials say, likely won't play Thursday night.

Further, after senior guard Erich Santifer and senior forward Leo Rautins played poorly against Georgetown, Coach Jim Boeheim said of them, "This is the time of year when our seniors should be carrying us. Recently, they haven't been doing that."

Of the second division--Pittsburgh, Connecticut, Providence and Seton Hall--the possibility of rocking the Big Five of the Big East lies most dangerously with Pitt. The Panthers are led by Claude Vaughan, a 6-4 junior forward, whose 15-foot jumpers from the lane rang up a 21.9 scoring average, best in the conference.