Serre's conjecture II (algebra)
Encyclopedia
In mathematics
, Jean-Pierre Serre
conjectured the following result regarding the Galois cohomology
of a simply connected
semisimple algebraic group
. Namely, he conjectured that if G is such a group over a field
F of cohomological dimension at most 2, then the Galois cohomology set H1(F, G) is zero.
The conjecture holds in the case where F is a local field
(such as p-adic field
) or a global field
with no real embeddings (such as Q(√−1)). This is a special case of the Kneser–Harder–Chernousov Hasse Principle for algebraic groups over global fields. (Note that such fields do indeed have cohomological dimension at most 2.)
The conjecture also holds when F is finitely generated over the complex numbers and has transcendence degree at most 2.
The conjecture is also known to hold for certain groups G. For special linear groups, it is a consequence of the Merkurjev-Suslin theorem. Building on this result, the conjecture holds if G is a classical group
. The conjecture also holds if G is one of certain kinds of exceptional group.
Mathematics
Mathematics is the study of quantity, space, structure, and change. Mathematicians seek out patterns and formulate new conjectures. Mathematicians resolve the truth or falsity of conjectures by mathematical proofs, which are arguments sufficient to convince other mathematicians of their validity...
, Jean-Pierre Serre
Jean-Pierre Serre
Jean-Pierre Serre is a French mathematician. He has made contributions in the fields of algebraic geometry, number theory, and topology.-Early years:...
conjectured the following result regarding the Galois cohomology
Galois cohomology
In mathematics, Galois cohomology is the study of the group cohomology of Galois modules, that is, the application of homological algebra to modules for Galois groups...
of a simply connected
Simply connected space
In topology, a topological space is called simply connected if it is path-connected and every path between two points can be continuously transformed, staying within the space, into any other path while preserving the two endpoints in question .If a space is not simply connected, it is convenient...
semisimple algebraic group
Semisimple algebraic group
In mathematics, especially in the areas of abstract algebra and algebraic geometry studying linear algebraic groups, a semisimple algebraic group is a type of matrix group which behaves much like a semisimple Lie algebra or semisimple ring.- Definition :...
. Namely, he conjectured that if G is such a group over a field
Field (mathematics)
In abstract algebra, a field is a commutative ring whose nonzero elements form a group under multiplication. As such it is an algebraic structure with notions of addition, subtraction, multiplication, and division, satisfying certain axioms...
F of cohomological dimension at most 2, then the Galois cohomology set H1(F, G) is zero.
The conjecture holds in the case where F is a local field
Local field
In mathematics, a local field is a special type of field that is a locally compact topological field with respect to a non-discrete topology.Given such a field, an absolute value can be defined on it. There are two basic types of local field: those in which the absolute value is archimedean and...
(such as p-adic field
P-adic number
In mathematics, and chiefly number theory, the p-adic number system for any prime number p extends the ordinary arithmetic of the rational numbers in a way different from the extension of the rational number system to the real and complex number systems...
) or a global field
Global field
In mathematics, the term global field refers to either of the following:*an algebraic number field, i.e., a finite extension of Q, or*a global function field, i.e., the function field of an algebraic curve over a finite field, equivalently, a finite extension of Fq, the field of rational functions...
with no real embeddings (such as Q(√−1)). This is a special case of the Kneser–Harder–Chernousov Hasse Principle for algebraic groups over global fields. (Note that such fields do indeed have cohomological dimension at most 2.)
The conjecture also holds when F is finitely generated over the complex numbers and has transcendence degree at most 2.
The conjecture is also known to hold for certain groups G. For special linear groups, it is a consequence of the Merkurjev-Suslin theorem. Building on this result, the conjecture holds if G is a classical group
Classical group
In mathematics, the classical Lie groups are four infinite families of Lie groups closely related to the symmetries of Euclidean spaces. Their finite analogues are the classical groups of Lie type...
. The conjecture also holds if G is one of certain kinds of exceptional group.