linguistics---

I want to know which process have the numbered words (Inflection or derivation).

1. go, goes, going, gone
2. discover, discovery, discoverer, discoverable, discoverability
3. lovely, lovelier, loveliest
4. inventor, inventor's, inventors, inventors'
5. democracy, democrat, democratic, democratize

[Tdol]

They have, in a sense, both- they are infections, suffixes, added to the root word from which they are derived.

I'd say 'go' is the root and the suffixes are inflections added to the others.
http://www.usingenglish.com/glossary/inflection.html