An ode to joy at the end: algebraic topology backwards
Spaces define the new number theory
How many goodly creatures are there here!
How beautious mankind is!
O brave new world, That has such people in't!"
Miranda in The Tempest.
1. Extensions of number systems
2. Negative numbers
3. Briefly on sheep
4. A trade deficit
5. Out in space
6. Ulla and Henriette live in RP∞
7. Negative sets
8. The sphere spectrum
9. Brave New World