The world preem of “Essential Self-Defense,” the latest play by Adam Rapp (“Red Light Winter”), will round out the 2006-07 season at Playwrights Horizons.Show, which concerns a misfit who takes a job as a dummy in a self-defense class and the rash of child disappearances in his Midwestern town, will be a co-production with Off Broadway troupe Edge Theater, which produced Rapp’s “Stone Cold Dead Serious.” Edge a.d. Carolyn Cantor will direct. Scribe’s “Red Light Winter” was a Pulitzer Prize finalist. His first film, “Winter Passing,” was released earlier this year. Rapp’s show joins a previously announced slate at Playwrights Horizons that includes “Frank’s Home,” a new play by Richard Nelson, and “Crazy Mary,” the latest from A.R. Gurney.