Create a new lean file with the name specified below in Game/Levels/content_drafts which correctly compiles and defines and proves the theorem below.
Break into intermediate theorems/lemmas if necessary (to go into separate levels, or provided as 'given' helpers, tbd later).
file name
topology_wrld_L03.lean
proof
preimage under continuous function of an open set is open
Game/Levels/content_draftswhich correctly compiles and defines and proves the theorem below. Break into intermediate theorems/lemmas if necessary (to go into separate levels, or provided as 'given' helpers, tbd later).topology_wrld_L03.leanSyllabus outline: #5