The problem is that patenting a kind of screw is not the same as patenting an algorithm or field of computer science. Software uses many more kinds algorithms t

The problem is that patenting a kind of screw is not the same as patenting an algorithm or field of computer science. Software uses many more kinds algorithms than any physical product uses screws. It's impossible to avoid minefields for any reasonably large project. Let's not forget that for quite a few years, asymmetric cryptography was patented and you couldn't implement any kind of cryptosystem that used it. God knows what the state of cryptography would be today if we didn't have our equivalent of a "dark age" thanks to fears over patent litigation.