In 2005, Dr. Helen Pilcher, the owner of a Ph.D. in Molecular Neurobiology who also happens to be a comedian, devised a mathematical formula to determine the success of a television sitcom. According to her, all you have to do is multiply the recognizability of the main character (r) by their delusions of grandeur (d), add that sum to the verbal wit of the script (v), then multiply the total by the amount someone falls over or suffers an injury (f). The difference in status between the highest and lowest characters is added (s), and the total is divided by the success of the show's scheme (a). Got that?

Anyway, Dr. Pilcher admits the whole thing is pseudo-scientific, but it, along with the overwhelmingly nostalgic TV posts on Pepsi Throwback's Facebook page, has inspired an examination of four classic sitcom types. Let's hope the wacky neighbor doesn't bust in while we are reviewing.

1. The Pas de Deux

The Pas de Deux sitcom formula is pretty simple to understand. It focuses on two people, and it's essentially an extended, agonizing game of "Will They or Won't They." Will the stuck-up, literate barmaid loosen the hell up enough to embrace the bro-of-bros borderline-idiot bartender who is always coming on to her? Will the chic and smart model-cum-P.I. finally let the fast-talking, fun-loving goofball make out with her face? Will the down-to-earth Colorado belle ever let an alien into her bed, despite her conservative father's disapproval? And so on.

2. Three Amigos Con Beneficios

Say a single girl, another single girl, and a single guy move in together. Escandaloso! So much so that the guy has to pretend he's gay in front of the suspicious landpeople, then explain that he's not in fact gay to the buxom blond pro-suntanner who lives next door. The key to the Three Amigos sitcom formula, is, well, the number three. Though the majority follow the girl-boy-girl or boy-girl-boy format, it can also be successful when applied to, say, three random straight dudes parenting a cadre of blond-haired children, or a trio of pre-pubescent suburbanites dealing with everything from mega zits to first kisses to a man landing on the moon.

3. Four Is Not the Loneliest Number

Some of our most beloved sitcom stars were part of a fearsome foursome. The loosely Aristotelian makeup of this winning formula is a hero, an anti-hero, a love interest, and a buddy. Go ahead, plug in, say, a comedian, his wacky neighbor, his ex-girlfriend, and his childhood best friend to that scenario. Or an unlucky-in-love New York chick, her bitchy gay neighbor, her ex-boyfriend who is now her gay best friend, and her mean, drunken, but ultimately caring co-worker. Again, this rhombus of love can take other forms, as in, for example, four senior ladies who live in pastels and caftans and chase geriatric men around Miami.

4. All Together Now

The Ensemble can encapsulate all of the previously-described forms: the will-they-won't-they couple, the love triangle, and the four buds all sitting together in one of several places, including, but not limited to: an unassuming Boston bar, a tiny Nantucket airport, an overpriced West Village apartment building, a taxi company, a Vermont bed and breakfast, a Manhattan courthouse, and a California high school headed by a pretty cool principal.

What have we learned? Sexual tension is always funny. And so are a bunch of people hanging out at work who would otherwise not ever hang out.

Want more? Just "like" Pepsi Throwback on Facebook, then click on the Random Acts tab on Facebook for all the classic sitcom fun times you can dream of!