It may be anathema to New Yorkers. But a team of mathematicians and engineers has calculated that if taxi riders were willing to share a cab, New York City could reduce the current fleet of 13,500 taxis up to 40 percent, in that way unclogging traffic, conserving fuel and fighting air pollution.

“The predicted economic and environmental savings are considerable,” said Steven Strogatz, a mathematician at Cornell and an author of a paper describing the findings, published Monday in Proceedings of the National Academy of Sciences.

The researchers wanted to know whether the principles of the “sharing economy” typified by services like Airbnb, in which people rent out their apartments like hotel rooms, could be applied to taxis.

“Think of how much spare capacity you have in taxis in New York City,” said another team member, Carlo Ratti, the director of the Senseable City Laboratory at the Massachusetts Institute of Technology. “You’re at a hotel, you’re going to J.F.K. Airport, and you take a taxi. And just minutes later, there’s somebody else taking another taxi, half empty, to J.F.K.”