Even if it'd be a good idea for your company to cut your allegedly under-performing coworker's wages (and it probably isn't a good idea for the company, either, as pointed out in several of the other answers) suggesting to do so as an employee is a bad idea and bound to back-fire, due to the psychological, social and office-political reasons also already mentioned in the other answers.
So what could you do instead?
You can ask (or even demand) equal pay for equal work
If performance cannot be measured or estimated, people who are given the same type and difficulty of tasks and are expected to perform similarly on them (due to comparable level of education and experience) should be paid the same.
Whether that is achieved by raising your pay or decreasing others' pay (or a combination of both) is then the employer's problem, not yours. Of course, if they only decrease your coworkers pay, you don't gain anything. But because cutting wages is usually a bad idea for the employer, too, they'll be unlikely to do that. Much more likely is that you'll get a raise.
Now, what equal work (except for equal duration) and equal difficulty are, is of course very subjective. To demonstrate your skills, you can suggest to switch tasks with some of your better-paid coworkers, so that your managers can see whether you can do that coworker's tasks just as satisfactorily as that coworker. Suggesting this is only a good idea if you're talked to that coworker in advance and they have agreed to it. So talk to a better-paid coworker that you get along with well, and who is also renowned to perform well. Even better is, if you can get your coworker to suggest the temporary task switch to your manager.
More viable is to have your better-paid and also-well-performing coworkers vouch for you. They are (and your managers probably know that) the ones who can estimate your contribution and (unmeasured) performance best, especially if tasks are tackled in close cooperation, where individual performance cannot be measured by definition, as a team can work better or worse than the individuals in it would work alone. If these people tell your common boss "<Mathematics' real name> helped me a lot recently. And he/she is also doing great work on his/her own tasks. Don't you think he/she should be paid the same as me?", that will count for quite something.
A word about experience: It is important (and you might have to make that clear to your managers) that the current experience i.e. including your experience gained in your current employment is considered, not the experience from back when you joined the company.
You can ask that low-paid or underpaid employees are considered for raises before already well-paid employees ...
... completely independent of whether performance, experience, difficulty and type of tasks are measured or estimated. People with low wages have more need for a raise and also gain more happiness from a raise of the same total height, than an already well-paid person does. And happy employees are more productive than unhappy ones, so a company might want to spend raise money where it produces the most happiness.
This suggestion, too, will have stronger impact, if you make it together with other coworkers, especially if already well-paid ones are also amongst them.
Now why would the already well-paid employees agree to that at all, thereby diminishing their own chances of getting (more) raises? Well, if you aren't working with a bunch of psychopaths, many of your well-paid co-workers will feel (or even know) that they themselves would gain more happiness by working with happier co-workers than by getting another raise.
That doesn't mean they'd agree to a cut for themselves, to enable a raise for you. Pay cuts make unhappy, even if the affected employee still has more than enough money afterwards. Psychology isn't rational.