Frances Moore Lappe, author of the groundbreaking "Diet For a Small Planet," will speak tonight from 7 to 9 p.m., with her daughter Anne Lappe (author of "Diet for a Hot Planet") at First Christian Church, 2201 First Av. S., Minneapolis. Cost is $15 (cash or check) at door. They will speak about their revolutionary ideas for transforming the food system. The program is sponsored by the Institute for Agriculture and Trade Policy.