Math 2.0

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Linear algebra

315 ideas in teaching order. Each idea comes after the ideas that it builds on. 312 of them have a page so far; the others are on the list in grey.

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  1. Linear equation definition
  2. System of linear equations definition
  3. Homogeneous system of linear equations definition
  4. Consistent and inconsistent systems definition
  5. Coefficient matrix definition
  6. Augmented matrix definition
  7. Elementary row operations definition
  8. Row equivalence definition
  9. Row echelon form definition
  10. Reduced row echelon form definition
  11. Pivot definition
  12. Gaussian elimination concept
  13. Gauss–Jordan elimination concept
  14. Back substitution concept
  15. Rouché–Capelli theorem statement
  16. Matrix definition
  17. Square matrix definition
  18. Zero matrix object
  19. Matrix addition definition
  20. Scalar multiplication of matrices definition
  21. Matrix–vector product definition
  22. Matrix multiplication definition
  23. Associativity of matrix multiplication statement
  24. Distributivity of matrix multiplication statement
  25. Non-commutativity of matrix multiplication counterexample
  26. Identity matrix object
  27. Matrix ring object
  28. Diagonal matrix definition
  29. Scalar matrix definition
  30. Upper triangular matrix definition
  31. Lower triangular matrix definition
  32. Transpose definition
  33. Transpose of a product statement
  34. Symmetric matrix definition
  35. Skew-symmetric matrix definition
  36. Conjugate transpose definition
  37. Hermitian matrix definition
  38. Block matrix definition
  39. Block diagonal matrix definition
  40. Trace of a matrix definition
  41. Trace is linear statement
  42. Trace of a transpose statement
  43. Trace of a product is symmetric statement
  44. Invertible matrix definition
  45. Inverse of a product statement
  46. One-sided inverse of a square matrix is two-sided statement
  47. General linear group object
  48. Elementary matrix definition
  49. Transvection definition
  50. Permutation matrix definition
  51. Computing the inverse by row reduction concept
  52. LU decomposition concept
  53. Nilpotent matrix definition
  54. Idempotent matrix definition
  55. Circulant matrix example
  56. Vector space definition
  57. Coordinate space object
  58. Space of matrices example
  59. Space of polynomials of bounded degree example
  60. Function space example
  61. Product of vector spaces definition
  62. Linear subspace definition
  63. Intersection of subspaces statement
  64. Sum of subspaces definition
  65. Linear combination definition
  66. Linear span definition
  67. Spanning set definition
  68. Linear independence definition
  69. Basis definition
  70. Standard basis object
  71. Every vector space has a basis statement
  72. Every spanning set contains a basis statement
  73. Every linearly independent set extends to a basis statement
  74. Steinitz exchange lemma statement
  75. Finite-dimensional vector space definition
  76. Dimension definition
  77. Dimension theorem for vector spaces statement
  78. Dimension of the coordinate space statement
  79. Dimension of a subspace statement
  80. A subspace of full dimension is the whole space statement
  81. Linearly independent set of the right size is a basis statement
  82. Grassmann's formula statement
  83. Coordinate vector definition
  84. Direct sum of subspaces definition
  85. External direct sum definition
  86. Dimension of a direct product statement
  87. Complementary subspaces definition
  88. Existence of a complementary subspace statement
  89. quotient space definition
  90. Quotient map definition
  91. Dimension of a quotient space statement
  92. Linear map definition
  93. Differentiation as a linear map example
  94. Composition of linear maps definition
  95. Kernel of a linear map definition
  96. Image of a linear map definition
  97. A linear map is injective iff its kernel is trivial statement
  98. A linear map is determined by its values on a basis statement
  99. Rank of a linear map definition
  100. Nullity definition
  101. Rank–nullity theorem statement
  102. Linear isomorphism definition
  103. Finite-dimensional spaces are isomorphic iff they have equal dimension statement
  104. Isomorphism with the coordinate space statement
  105. An injective endomorphism of a finite-dimensional space is surjective statement
  106. First isomorphism theorem for linear maps statement
  107. Second isomorphism theorem for vector spaces statement
  108. Third isomorphism theorem for vector spaces statement
  109. Universal property of the quotient space statement
  110. Space of linear maps definition
  111. Dimension of the space of linear maps statement
  112. Endomorphism definition
  113. Algebra of endomorphisms object
  114. Projection definition
  115. Matrix of a linear map definition
  116. Linear map of a matrix definition
  117. Multiplication by a matrix as a linear map definition
  118. Matrix of a composition is the product of matrices statement
  119. Column space definition
  120. Row space definition
  121. Null space definition
  122. Rank of a matrix definition
  123. Row rank equals column rank statement
  124. Rank of a product of matrices statement
  125. Change of basis matrix definition
  126. Change of basis formula statement
  127. Similar matrices definition
  128. Equivalent matrices definition
  129. Trace of a linear map definition
  130. Trace of a linear map is the trace of its matrix statement
  131. Linear form definition
  132. Dual space definition
  133. Dual basis definition
  134. Dimension of the dual space statement
  135. Canonical isomorphism with the double dual statement
  136. Annihilator of a subspace definition
  137. Dimension of the annihilator statement
  138. Dual map definition
  139. Matrix of the dual map is the transpose statement
  140. Multilinear map definition
  141. Alternating multilinear map definition
  142. Determinant definition
  143. Leibniz formula for determinants statement
  144. Determinant of a 2 by 2 matrix statement
  145. Rule of Sarrus statement
  146. Determinant is multilinear in the rows statement
  147. Determinant of a matrix with two equal rows statement
  148. Determinant of a matrix with a zero row statement
  149. Scaling a row scales the determinant statement
  150. Adding a multiple of one row to another preserves the determinant statement
  151. Permuting rows multiplies the determinant by the sign statement
  152. Determinant of the identity matrix statement
  153. Determinant of a triangular matrix statement
  154. Determinant of a transpose statement
  155. Determinant is multiplicative statement
  156. Determinant of a scalar multiple statement
  157. Determinant of the inverse statement
  158. A matrix is invertible iff its determinant is a unit statement
  159. Determinant of a block triangular matrix statement
  160. Minor definition
  161. Cofactor definition
  162. Laplace expansion along a row statement
  163. Laplace expansion along a column statement
  164. Adjugate matrix definition
  165. Product of a matrix and its adjugate statement
  166. Inverse in terms of the adjugate statement
  167. Cramer's rule statement
  168. Vandermonde determinant statement
  169. Cauchy–Binet formula statement
  170. Determinant via the Schur complement statement
  171. Sylvester's determinant theorem statement
  172. Matrix determinant lemma statement
  173. Determinant of a linear map definition
  174. Determinant of a linear map is the determinant of its matrix statement
  175. Determinant of a family of vectors in a basis definition
  176. Determinant as signed volume concept
  177. Special linear group object
  178. Orientation of a real vector space definition
  179. Eigenvalue definition
  180. Eigenvector definition
  181. Eigenspace definition
  182. Spectrum of a matrix definition
  183. Characteristic polynomial definition
  184. Characteristic polynomial of a linear map definition
  185. Characteristic polynomial does not depend on the basis statement
  186. Eigenvalues are the roots of the characteristic polynomial statement
  187. Trace is a coefficient of the characteristic polynomial statement
  188. Determinant is a coefficient of the characteristic polynomial statement
  189. Trace is the sum of the eigenvalues statement
  190. Determinant is the product of the eigenvalues statement
  191. Eigenvectors with distinct eigenvalues are linearly independent statement
  192. Algebraic multiplicity definition
  193. Geometric multiplicity definition
  194. Existence of an eigenvalue over an algebraically closed field statement
  195. Gershgorin circle theorem statement
  196. Polynomial of an endomorphism definition
  197. Annihilating polynomial definition
  198. minimal polynomial definition
  199. Minimal polynomial divides every annihilating polynomial statement
  200. Eigenvalues are the roots of the minimal polynomial statement
  201. Cayley–Hamilton theorem statement
  202. Cayley–Hamilton theorem for linear maps statement
  203. Minimal polynomial divides the characteristic polynomial statement
  204. Diagonalisable matrix definition
  205. A matrix is diagonalisable iff it has a basis of eigenvectors statement
  206. Distinct eigenvalues imply diagonalisable statement
  207. Diagonalisable iff the minimal polynomial has distinct roots statement
  208. Powers of a diagonalisable matrix concept
  209. Simultaneous diagonalisation statement
  210. Invariant subspace definition
  211. Restriction of an endomorphism to an invariant subspace definition
  212. Triangularisation statement
  213. Generalised eigenspace definition
  214. Generalised eigenvector definition
  215. Decomposition into generalised eigenspaces statement
  216. Nilpotent endomorphism definition
  217. Jordan block definition
  218. Jordan normal form statement
  219. Semisimple endomorphism definition
  220. Jordan–Chevalley decomposition statement
  221. Companion matrix definition
  222. Rational canonical form statement
  223. Matrix exponential definition
  224. Exponential of a sum of commuting matrices statement
  225. Determinant of a matrix exponential statement
  226. Dot product definition
  227. Inner product definition
  228. Inner product space definition
  229. Norm definition
  230. Normed vector space definition
  231. Norm induced by an inner product definition
  232. Cauchy–Schwarz inequality statement
  233. Triangle inequality for norms statement
  234. Parallelogram law statement
  235. Polarisation identity statement
  236. Orthogonal vectors definition
  237. Pythagorean theorem in an inner product space statement
  238. Orthonormal family definition
  239. An orthonormal family is linearly independent statement
  240. Orthonormal basis definition
  241. Gram–Schmidt process concept
  242. Gram–Schmidt vectors are orthogonal statement
  243. Existence of an orthonormal basis statement
  244. Coordinates in an orthonormal basis statement
  245. Bessel's inequality statement
  246. Parseval's identity statement
  247. Orthogonal complement definition
  248. A space is the direct sum of a subspace and its orthogonal complement statement
  249. Dimension of the orthogonal complement statement
  250. Orthogonal complement of the orthogonal complement statement
  251. Orthogonal projection definition
  252. Orthogonal projection is the closest point statement
  253. Least squares concept
  254. Gram matrix definition
  255. Riesz representation theorem in finite dimensions statement
  256. Adjoint of a linear map definition
  257. Matrix of the adjoint is the conjugate transpose statement
  258. Self-adjoint operator definition
  259. Eigenvalues of a self-adjoint operator are real statement
  260. Eigenspaces of a self-adjoint operator are orthogonal statement
  261. Spectral theorem statement
  262. Spectral theorem for Hermitian matrices statement
  263. Rayleigh quotient definition
  264. Normal operator definition
  265. Normal matrix definition
  266. Spectral theorem for normal matrices statement
  267. Linear isometry definition
  268. A linear isometry preserves the inner product statement
  269. Orthogonal matrix definition
  270. Orthogonal group object
  271. Special orthogonal group object
  272. Unitary matrix definition
  273. Unitary group object
  274. Rotation matrix example
  275. Reflection definition
  276. Cartan–Dieudonné theorem statement
  277. QR decomposition statement
  278. Positive definite matrix definition
  279. Positive semidefinite matrix definition
  280. Eigenvalues of a positive definite matrix are positive statement
  281. Gram matrices are positive semidefinite statement
  282. Sylvester's criterion statement
  283. Cholesky decomposition statement
  284. Square root of a positive semidefinite matrix definition
  285. Singular value definition
  286. Singular value decomposition statement
  287. Polar decomposition statement
  288. Moore–Penrose inverse definition
  289. Bilinear form definition
  290. Matrix of a bilinear form definition
  291. Change of basis for a bilinear form statement
  292. Symmetric bilinear form definition
  293. Alternating bilinear form definition
  294. Nondegenerate bilinear form definition
  295. Orthogonal family for a bilinear form definition
  296. Sesquilinear form definition
  297. Quadratic form definition
  298. Polar form of a quadratic form definition
  299. Symmetric bilinear form associated with a quadratic form definition
  300. Diagonalisation of a quadratic form statement
  301. Sylvester's law of inertia statement
  302. Signature of a quadratic form definition
  303. Classification of complex quadratic forms statement
  304. positive definite quadratic form definition
  305. Principal axis theorem statement
  306. Tensor product of vector spaces definition
  307. Universal property of the tensor product statement
  308. Basis of a tensor product statement
  309. Dimension of a tensor product statement
  310. Kronecker product definition
  311. Exterior algebra definition
  312. Module over a ring definition
  313. Submodule definition
  314. Free module definition
  315. Finitely generated module definition