Introduction to Group Theory (Paperback)

'I Definition of a Group and Examples.- 1 The abstract group and the notion of group isomorphism.- a. Sets and mappings.- b. Algebraic systems.- c. Semigroups.- d. Groups.- e. Isomorphism.- f. Cyclic groups 7.- Examples and exercises.- 2 Groups of mappings. Permutations. Cayley's theorem.- a. Composition of mappings.- b. Permutations.- c. Cycles.- d. Transpositions.- e. Subgroups.- f. Cayley's theorem. The group table.- Examples and exercises.- 3 Arithmetical groups.- a. Facts of number theory.- b. Residue classes modulo m. Euler's function.- c. The unit group of a ring.- d. Matrix residue class groups (mod m).- e. The case m = 2.- Examples and exercises.- 4 Geometrical Groups.- a. Rotations and reflexions.- b. The dihedral groups.- c. Rotations and reflexions in space.- d. The polyhedral groups.- e. The groups of the octahedron and of the tetrahedron.- Examples and exercises.- II Subsets, Subgroups, Homomorphisms.- 1 The algebra of subsets in a group.- a.-c. Product and inverse of subsets.- d. Subgroup generated by a subset.- e. Two disjoint subsets covering a group.- Examples and exercises: Frattini subgroup.- 2 A subgroup and its cosets. Lagrange's theorem.- a. Cosets. Lagrange's theorem.- b. Index theorems.- c. Poincare's theorem.- d. Finite cyclic groups.- Examples and exercises: Multiplicative group of a finite field. The icosahedral group. Frattini subgroup. Abelian groups.- 3 Homomorphisms, normal subgroups and factor groups.- a. Homomorphism, epimorphism, monomorphism.- b. Kernel.- c. Natural homomorphism and factor group.- d. Canonical product.- Examples and exercises.- 4 Transformation. Conjugate elements. Invariant subsets.- a. Conjugacy.- b. Invariance..- c. The classes.- d. The normalizer.- e. Generalization of Cayley's theorem.- Examples and exercises: Transformation in permutation groups. Geometry in a group.- 5 Correspondence theorems. Direct products.- a.-b. Theorems.- c. The internal direct product.- d. Generalization to more than two factors.- e. The external direct product.- f. The restricted direct product.- Examples and exercises.- 6 Double cosets and double transversals.- a. A counting formula.- b. Double cosets.- c. Double transversals.- d. A group of double cosets.- Examples and exercises.- III Automorphisms and Endomorphisms.- 1 Groups of automorphisms. Characteristic subgroups.- a. Generalities.- b. Inner automorphisms.- c. Characteristic subgroups.- d. Characteristically simple groups.- e. ?-invariance.- Examples and exercises: Automorphism groups of some special groups. Simplicity of the alternating groups. The kernel or nucleus of a group. The Frattini subgroup, a characteristic subgroup.- 2 The holomorph of a finite group. Complete groups.- a. Definition of the holomorph.- b.-c. The holomorph as a permutation group.- d. Is the holomorph minimal?.- e. Complete groups.- Examples and exercises: Completeness of the symmetric groups. Equicentralizer systems in groups.- 3 Group extensions.- a. The semi-direct product.- b. The external semi-direct product.- c. Are there other solutions to the extension problem ?.- d.-e. Construction of a normal extension.- Examples and exercises: Complement. Splitting extension.- 4 A problem of Burnside: Groups with outer automorphisms leaving the classes invariant.- a. Preliminaries on the groups L2n.- b. The groups L4n and L8n.- c. Automorphism associated with a subgroup of index 2.- d. Proof of the theorem concerning L8n.- Examples and exercises.- 5 Endomorphisms and operators.- a. Endomorphisms.- b. The endomorphism ring of an abelian group.- c. Operator domain of a group. Fully invariant subgroups.- Examples and exercises.- IV Finite Series of Subgroups.- 1 The fundamental concepts of lattice theory.- a. Partially ordered sets.- b. Lattices.- c. Partially ordered set and lattice.- d. Modular lattices and distributive lattices.- Examples and exercises.- 2 Lattices of