If momentum plays a part in the world of international show jumping, Ted Edgar of Great Britain, Ian Millar of Canada and Mike Matz of the United States should be winners at the Washington International Horse Show this week.

All three come into Capital Centre with recent major victories - Edgar in the Horse of the Year show at Wembley, England last week; Millar in the Canadian Jumping Derby at Aurora, Ontario, in September and Matz in the $50,000 American Jumping Derby at Portsmouth, N. H., earlier this month.

The three will join nearly 50 other riders, representing the finest equestrian talent in the world, in the international-open competition that highlights eight of the nine days of the show.

The 19th edition of the event opens tonight in typical American fashion.

Promptly at 7:30 p.m. the Centre turning barrel racing and pole bending as well as classes for Western, Appaloosa and Arabian horses.

Tequila Sham, the toast of opening night last year, is expected to return to defend its Cloverleaf Barrel championship while Honey Gold, Gretchen Rivers' 8 year old palomino, will attempt to repeat in the Pole Bending competition.

Nightly appearances by the world famous Tempel Lipizzans are scheduled as well as the appearances of the famed Courvoisier Arabian.

Hunt Night, one of the real sporting events of the show, is scheduled for Wednesday evening starting at 5 p.m. The newest feature of the show, Pony Club competition, is scheduled for Monday through Thursday evenings.

The international open jumping will begin Sunday evening, International Night. The Puissance on Tuesday, the Eisenhower on Thursday afternoon, the Nations Cup on Friday evening and the famed President's Cup on Sunday evening are events most prized by the riders.

Edgar will team with his wife, Liz, Tim Grubb and John Whitaker as representatives of Great Britain. Miller joins Terry Leibel, John Simpson and Terrance (Torchy) Miller carrying the colors of Canada.

Olympic gold medalist Alwin Schockemoehle, a veteran of many visits to the Washington show, leads the West German team, although he comes as the coach and not as a competitor. Willibert Mehikopf, Lutz Merkel, Hendrick Schulze-Siehoff and Achaz Von Buchwaldt make up the young German team.

William (Buddy) Brown, Conrad Homfeld and Joe Fargis join Matz as one of the youngest, but possibly the strongest, team to represent the United States in the show's history.

Rodney Jenkins leads the largest contingent of open riders who will match their skills and horses against the national teams. Except for the prix des Nations on Friday evening, all jumping events are open to both team and open riders.

Next Saturday and Sunday will be devoted exclusively to junior and pony competition during the daytime programs. The amateur-owners clashes begin Thursday.