Science and maths have never been the preserve of lone geniuses: collaboration has always been at the heart of intellectual endeavour. But to this day, men like Einstein remain the pervasive archetype of genius, and the intellectual contributions of women past and present have gone unacknowledged. x+y is one mathematician's manifesto for how we can fix that - and why that requires rethinking how we think about thinking itself.In her illuminating new book, Royal Society Book Prize finalist Eugenia Cheng reveals how mathematics can help us escape gendered stereotypes by giving us new structures based on character, not gender. By reframing intellectual endeavour beyond the myth of the lone genius, she shows that the real key to success is thinking more collaboratively. x+y shows us how one small but powerful change to the way we think could make the world a better place for men and women alike.