It's all about the algorithm.

Entering the offices of Match.com is a bit like strutting into a disco. Coloured lights flash from the ceilings, workers lounge on circular banquettes, dance music plays from hidden speakers. Despite being in a mid-rise office tower overlooking a turnpike in the dry, landlocked city of Dallas, Texas, the Match offices are evocative of a racier environment, where anything might happen.

On a hazy Monday in June, I came to meet Mandy Ginsberg, the president of Match.com US, the world's largest online dating site. Petite, preppy and freckled, with long brown hair, Ginsberg was wearing sandals, tight black jeans and a loose blouse. Her jewellery was limited to a diamond bracelet and a wedding band. Confident and casual, she seemed as good a person as any to be the face of online dating. We sat in a conference room ­overlooking a floor full of computer engineers gazing at their monitors, and with a PowerPoint presentation, she endeavoured to show me how Match uses cutting-edge ­technology to cultivate age-old emotions.

With the number of paying subscribers using Match approaching 1.8 million, the ­company has had to develop ever more ­sophisticated programs to manage, sort and pair the world's singles. Central to this effort has been the development, over the past two years, of an improved matchmaking algorithm. "We had to get more ­intelligent," Ginsberg says. "If you say you want a guy between 30 and 35 in New York who has a master's degree, you're going to get thousands of matches."

Codenamed "Synapse", the Match algorithm uses a variety of factors to suggest possible mates. While taking into account a user's stated ­preferences, such as desired age range, hair colour and body type, it also learns from their actions on the site. So, if a woman says she doesn't want to date anyone older than 26, but often looks at ­profiles of thirty-somethings, Match will know she is in fact open to meeting older men. Synapse also uses "triangulation". That is, the algorithm looks at the behaviour of similar users and factors in that ­information, too.

Until Ginsberg joined IAC, which owns Match, in 2006, she worked at i2 Technologies, a supply-chain management company, also based in Dallas. She was promoted to her current post earlier this year, after former Match president Gregg Blatt was made chief executive officer of IAC. Besides having the right résumé for the job, Ginsberg had enough experience in love to know that ­finding the right partner is tough.

After a divorce shortly out of college, she tried JDate, a site for Jewish singles, but kept coming up short. Then, while still at i2, she became involved with an engineer at the company who was born halfway across the world. They soon married. "If I had laid out a criteria for what I was looking for, it would not have been a guy from south India," she told me. "People are complex. You're constantly making trade-offs about who's too tall, too short, too smart and too dumb. People come in and tell us a bit about what they're looking for. But what you say and what you do can be different."

Academics call this "dissonance". "It's a theme that runs through social psychological literature," says Andrew Fiore, a visiting assistant professor at Michigan State University, who works on ­computer-mediated communication. "We don't know ourselves very well on a descriptive level."

The same is true for the millions of Match users, says Ginsberg, and she tried to incorporate dissonance into the algorithm. "I might come in and say I'm looking for a nice Catholic guy between 30 and 40 who is non-married," she says. "But after weeks of looking at people, I might get an e-mail from a guy who has kids, and I might accept that. It's all about behaviour modelling. All that data goes into algorithms and affects who we put in front of you."

To sort expressed ideals from actual desires, Ginsberg realised she would need some technical help. After becoming executive vice-president and general manager of Match's North American operations in 2008, Ginsberg initially looked to her old employer, i2, for assistance. "I brought over a bunch of people who I thought could help solve one of the most difficult problems out there, which is how to model human attraction," she says.

A key recruit was Amarnath Thombre, a soft-spoken engineer from Pune, India. Thombre had attended the prestigious Indian Institute of Technology Bombay, then taken an advanced degree in chemical engineering at the University of Arizona. Like his boss, he met the love of his life offline. His wife is also Indian, and they were introduced through family.