At 3, a cycle sponsored by Friends of the Greenwich Library begins with the Shanghai Quartet in the library's Cole Auditorium (622-7965).

Public Library, Cole Auditorium, 101 West Putnam Avenue.

TIBETANS IN FLIGHT "A Song for Tibet," a documentary film by Ann Henderson, filmed in India and Montreal, will be shown today at 5 P.M. in the Cole Auditorium of the Greenwich Library.

Cole Auditorium, 101 West Putnam Avenue.

The afternoon presentation is at the Cole Auditorium of the Greenwich Library, 101 West Putnam Avenue.

Also at the Cole Auditorium the following day and with a $3 admission, next Sunday from 2 to 3 P.M. Clyde Roper, curator, of the department of invertebrate zoology, National Museum of Natural History, will present "Mystery of the Giant Squid," an illustrated slide lecture.

Each of these costs $3 and takes place at the Cole Auditorium from 7:30 to 8:30 P.M.

Another free Library concert of note next Sunday afternoon - this one at 4 P.M. - brings the Brentano String Quartet to Cole Auditorium in Greenwich.

Thinking Ahead "Estate Planning Strategies: Avoiding Near-Death Tax Experiences and Bad Heir Days" is the title of a program to be presented on Wednesday at 7:30 in the Cole Auditorium of the Greenwich Library.

"Great Patrons of Renaissance Italy" is scheduled at 8 P.M. Thursday in the Cole Auditorium of the Greenwich Library, 101 West Putnam Avenue.