Now, the new rules which go into effect this summer have changed things a little (though the basic principle remains the same).
(the new rules; go; into effect; T:this summer) (the new rules which go into effect this summer; have changed; things; T:Now) (the basic principle; remains; the same)
the new rules the new rules which go into effect this summer the basic principle
go have changed remains
into effect T:this summer
things T:Now
the same