mathematics, the annulus theorem (formerly called the annulus conjecture) states roughly that the region between two well-behaved spheres is an annulus. It is closely...

shaped like a ring or a hardware washer. The word "annulus" is borrowed from the Latin word anulus or annulus meaning 'little ring'. The adjectival form is...

cobound a properly embedded annulus. This should not be confused with the high dimensional theorem of the same name. The torus theorem is as follows: Let M be...

homeomorphism of an annulus that rotates the two boundaries in opposite directions has at least two fixed points. The Poincaré–Birkhoff theorem was discovered...

{bh^{3}}{12}}+{\frac {hb^{3}}{12}}={\frac {bh}{12}}\left(b^{2}+h^{2}\right)} Consider an annulus whose center is at the origin, outside radius is r 2 {\displaystyle r_{2}}...

Seifert–Van Kampen theorem of algebraic topology (named after Herbert Seifert and Egbert van Kampen), sometimes just called Van Kampen's theorem, expresses the...

quantum mechanics, the Byers–Yang theorem states that all physical properties of a doubly connected system (an annulus) enclosing a magnetic flux Φ {\displaystyle...

shell theorem gives gravitational simplifications that can be applied to objects inside or outside a spherically symmetrical body. This theorem has particular...

Pappus's centroid theorem (also known as the Guldinus theorem, Pappus–Guldinus theorem or Pappus's theorem) is either of two related theorems dealing with...

z ) {\displaystyle f(z)} will then be valid anywhere inside the annulus. The annulus is shown in red in the figure on the right, along with an example...