Abhyankar's inequality
Abhyankar's inequality is an inequality involving extensions of valued fields in algebra, introduced by . Abhyankar's inequality states that for an extension K/k of valued fields, the transcendence degree of K/k is at least the transcendence degree of the residue field extension plus the rank of the quotient of the valuation groups; here the rank of an abelian group  is defined as . References

Field (mathematics)
Commutative algebra
Theorems in abstract algebra