Joint Filing Agreement ----------------------

                                                                       EXHIBIT 4
                                                                       ---------

                             Joint Filing Agreement
                             ----------------------

         Each of the undersigned hereby acknowledges and agrees, in compliance
with the provisions of Rule 13d-1(k)(1) promulgated under the Securities
Exchange Act of 1934, as amended, that the Schedule 13D to which this Agreement
is attached as an Exhibit (the "Schedule 13D"), and any amendments thereto, will
be filed with the Securities and Exchange Commission jointly on behalf of the
undersigned. This Agreement may be signed by the undersigned in separate
counterparts.

Dated: February 22, 1999

                                          THE BERKSHIRE COMPANIES LIMITED 
                                          PARTNERSHIP


                                          By: KGP-1, Inc., 
                                              its General Partner
                                              
                                              By: /s/ Xxxxxxx Xxxxx
                                              ---------------------
                                              Name:  Xxxxxxx Xxxxx
                                              Title: President


                                          KGP-1, INC.

                                          By: /s/ Xxxxxxx Xxxxx
                                          ---------------------
                                          Name:  Xxxxxxx Xxxxx
                                          Title: President


                                          KGP-2, INC.

                                          By: /s/ Xxxxxxx Xxxxx
                                          ---------------------
                                          Name:  Xxxxxxx Xxxxx
                                          Title: President


                                          /s/ Xxxxxxx Xxxxx
                                          -----------------
                                          Xxxxxxx Xxxxx



                                                                               2
                                                       *
                                          ____________________________
                                          Xxxxxx Xxxxx


                                          * By: /s/ Xxxxxxx Xxxxx
                                            ---------------------
                                            Name:  Xxxxxxx Xxxxx
                                            Title: Attorney-in-fact