- #1

- 31

- 0

## Main Question or Discussion Point

Hello !

When I'm reading something about differential equations everywhere it's about open sets. For example when we define special kind of equation

[tex]x'=f(t,x)\,;\;f:\Omega\subset\mathbb{R}\times\mathbb{R}\to\mathbb{R}[/tex]

Omega is open. Why Omega must be open? Thanks

When I'm reading something about differential equations everywhere it's about open sets. For example when we define special kind of equation

[tex]x'=f(t,x)\,;\;f:\Omega\subset\mathbb{R}\times\mathbb{R}\to\mathbb{R}[/tex]

Omega is open. Why Omega must be open? Thanks