Radia Perlman
Solved a problem holding back computer networks in a weekend and wrote the algorithm as a poem
Radia Perlman was good at maths and science at school but, she has said, had no idea what an engineer did and was uncomfortable being the only girl in the room. At MIT she found herself in a lab full of people who had been building electronics since childhood. She had not, and it took her time to believe she belonged there. While still a student she designed a version of the LOGO programming language that children as young as three could use, with a keyboard of big buttons.
In 1980 she joined Digital Equipment Corporation, where the problem was how to link Ethernet networks together. Connecting them with bridges was easy, but if the connections formed a loop, messages circulated for ever and the network collapsed. Her manager asked her to look at it. She worked out the answer, a way for the bridges to elect a root and agree on a single tree of paths, in a day or two, and wrote the specification within a week. She also wrote a short poem, Algorhyme, summarising how it worked.
The spanning tree protocol became a standard and is still running in most networks. She went on to design the routing protocol IS-IS, write a widely used textbook and hold more than a hundred patents. She dislikes being called the mother of the internet, pointing out that it had many parents.