Nineteenth-century playwright Anton Chekhov revolutionized theater with his bold decision to focus his lens on character psychology rather than plot. There is perhaps no better example of this than Uncle Vanya, which follows a disillusioned family of landed gentry in rural Russia. Vermont Repertory Theatre mounts David Mamet’s contemporary adaptation of Chekhov’s masterpiece at Main Street Landing Performing Arts Center, where unrequited love, jealousy and despair are catalysts for … laughter! Though heavily imbued with existential aching, the company reminds us that, at its core, the play is “a comedy with its teeth bared — the kind where people tell jokes just before their souls collapse.”