Zorich's theorem
In mathematical analysis, Zorich's theorem was proved by Vladimir A. Zorich in 1967.{{cite journal
| last = Zorič | first = V. A.
| journal = Proceedings of the USSR Academy of Sciences
| mr = 223568
| pages = 31–34
| title = Homeomorphism of quasiconformal space maps
| volume = 176
| year = 1967}} As cited by {{harvtxt|Zorich|1992}} The result was conjectured by M. A. Lavrentev in 1938.{{cite journal
| last = Lavrentieff | first = M.
| journal = Proceedings of the USSR Academy of Sciences
| pages = 241–242
| title = Sur un critère différentiel des transformations homéomorphes des domaines à trois dimensions.
| volume = 20
| year = 1938}} As cited by {{harvtxt|Zorich|1992}}
Theorem
Every locally homeomorphic quasiregular mapping for , is a homeomorphism of .{{cite book |last=Zorich |first=Vladimir A. |author-link=Vladimir A. Zorich |editor-last=Vuorinen |editor-first=Matti |editor-link=Matti Vuorinen |year=1992 |chapter=The global homeomorphism theorem for space quasiconformal mappings, its development and related open problems |pages=132–148 |title=Quasiconformal Space Mappings: A collection of surveys 1960-1990 |series=Lecture Notes in Mathematics |volume=1508 |publisher=Springer-Verlag |publication-place=Germany |doi=10.1007/BFB0094243 |isbn=3-540-55418-1 |lccn=92012192 |oclc=25675026 |s2cid=116148715 |chapter-url={{GBurl|fo58CwAAQBAJ|p=132}} |access-date=February 10, 2024}}
The fact that there is no such result for is easily shown using the exponential function.{{sfnp|Zorich|1992|p=135}}