Linear and multilinear algebra; matrix theory Proof
Proof that the determinant of the identity matrix is one
Builds on DeterminantIdentity matrix
Proof
- Let be the identity matrix over .
- By property 3 of the definition of the determinant, .
Idea
The determinant is fixed by three properties, and the value on the identity is one of them. This normalization picks one function out of all alternating multilinear functions, which differ from it by a constant factor.
Reading path
To understand this page from the ground up, read these 9 pages in order. The foundations come first.
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- no evidence level
- Identity matrix object
- Matrix definition
- Vector space definition
- Square matrix definition
- Linear map definition
- Multilinear map definition
- Alternating multilinear map definition
- Determinant definition
- Proof that the determinant of the identity matrix is one proof
Where this leads
246 pages build on this one.
- Singular value decomposition
- Change of variables in multiple integrals
- Lotka–Volterra equations
- Volume of a ball in R^n
- Leibniz formula for determinants
- Triangularisation
- A matrix is invertible iff its determinant is a unit
- Lagrange multiplier with one constraint
- Determinant is multiplicative
- Spectral theorem for normal matrices
- Product of a matrix and its adjugate
- Eigenvalues are the roots of the characteristic polynomial
- Scalar triple product
- Jacobian of spherical coordinates
- Laplace expansion along a column
- Spectral theorem
- Determinant of the inverse
- Existence of an eigenvalue over an algebraically closed field
- Cauchy–Binet formula
- Minimal polynomial divides the characteristic polynomial
- Cramer's rule
- Liouville's formula
- Linearisation at an equilibrium
- Determinant of a matrix exponential
- Matrix determinant lemma
- Implicit function theorem
- Laplace expansion along a row
- Determinant is the product of the eigenvalues
- Hyperbolic equilibrium point
- Spectral theorem for Hermitian matrices
- Inverse in terms of the adjugate
- QR decomposition
- Cayley–Hamilton theorem
- Trace is a coefficient of the characteristic polynomial
- Sylvester's determinant theorem
- Cylindrical coordinates
- Rule of Sarrus
- Polar decomposition
- Determinant of a block triangular matrix
- Determinant of a triangular matrix
- Inverse function theorem
- Determinant via the Schur complement
- Determinant of a linear map is the determinant of its matrix
- Wronskian test for linear independence of solutions
- Classification of equilibria of planar linear systems
- Implicit function theorem for a surjective derivative
- Trace is the sum of the eigenvalues
- Vandermonde determinant
- Principal axis theorem
- Cayley–Hamilton theorem for linear maps
- Implicit differentiation
- Polar coordinates
- Spherical coordinates
- Variation of constants formula for linear systems
- Hartman–Grobman theorem
- Pendulum equation
- Stability of linear systems via eigenvalues
- Determinant is a coefficient of the characteristic polynomial
- Integration in polar coordinates
- Characteristic polynomial does not depend on the basis
- Lagrange multipliers
- Sylvester's criterion
- Cholesky decomposition
- Volume of a ball in R^3
- Diffeomorphism
- Decomposition into generalised eigenspaces
- Determinant of the identity matrix
- Local homeomorphism from the inverse function theorem
- Determinant of a 2 by 2 matrix
- Determinant of a transpose
- Morse–Smale system
- Spectral theorem for unbounded self-adjoint operators
- Proof of the Lagrange multiplier rule with one constraint
- Routh–Hurwitz theorem
- Proof of the principal axis theorem from the spectral theorem
- Cuthill–McKee algorithm
- Hautus lemma
- Holomorphic inverse function theorem
- Proof of the implicit function theorem for a surjective derivative
- Proof of the singular value decomposition from the spectral theorem
- Jacobi's formula
- Proof of the implicit function theorem from the inverse function theorem
- Quantum Zeno effect
- Hilbert–Schmidt expansion theorem
- Proof of the Laplace expansion along a column by transposition
- Duality of controllability and observability
- Markov partition
- Augmented Lagrangian method
- Minimal realization
- Proof of the Schur complement formula by block factorization
- Minimum degree algorithm
- Proof of Cramer's rule by the adjugate
- Proof that the scalar triple product is a determinant
- Anharmonic oscillator
- Proof of Sylvester's criterion by induction and completing the square
- Proof of the Wronskian test for linear independence of solutions
- Volterra's principle
- Bilinear series of a symmetric kernel
- Choquet-Bruhat–Geroch theorem on maximal developments
- Proof of the Lagrange multiplier theorem by the implicit function theorem
- QR algorithm
- Spectral decomposition theorem
- Black hole stability problem
- Mason's gain formula
- Sylvester's determinant identity
- Proof that the constant coefficient of the characteristic polynomial is a signed determinant
- Incomplete Cholesky factorization
- Proof that the determinant is multiplicative by expanding the rows
- Central polynomial
- Box–Muller transform
- Kaplansky's theorem on PI rings
- Proof that a matrix is invertible iff its determinant is a unit
- Proof that the trace is the sum of the eigenvalues by comparing coefficients
- Proof of the determinant of a block triangular matrix by the Leibniz formula
- Nested dissection
- Uhlmann's theorem
- Kalman rank condition
- Marshallian demand function
- Proof that a C^1 map with invertible derivative is a local homeomorphism and an open map
- Nash–Moser theorem
- Spectral theorem for compact self-adjoint operators
- Courant–Fischer characterization of characteristic values
- Proof of Liouville's formula
- Utility maximization problem
- Proof of the spectral theorem for self-adjoint operators by induction on the dimension
- Proof of the Laplace expansion along a row by the Leibniz formula
- Principle of material frame-indifference
- Detectability
- Mixed state
- Implicit function theorem in Banach spaces
- Melnikov method
- Strong cosmic censorship conjecture
- Euler's elastica
- Proof that the determinant of a transpose equals the determinant
- Lyapunov–Schmidt reduction
- Purification of a quantum state
- Gleason's theorem
- Weak cosmic censorship conjecture
- Numerical continuation
- Proof of the inverse in terms of the adjugate
- Proof of the eigenvalue criteria for stability of linear systems via the Jordan normal form
- Inverted pendulum
- Proof that the trace is a coefficient of the characteristic polynomial by the Leibniz formula
- Schur polynomial
- Stone's theorem on one-parameter unitary groups
- Closing lemma
- Sequential quadratic programming
- Kalman decomposition
- Anosov flow
- Lidskii's trace formula for integral operators
- Hamiltonian operator
- Second quantization
- Differential-algebraic system of equations
- Proof of the decomposition into generalised eigenspaces
- Smale's problems on dynamics
- Controllability Gramian
- Posner's theorem
- Controllable canonical form
- Spectrum of the Laplace–Beltrami operator
- Backus–Gilbert method
- Principal stresses
- Furuta pendulum
- Topological quantum field theory
- Smooth dynamical system
- Brunovsky normal form
- Wick rotation
- Eckart–Young theorem
- Balanced truncation
- Ackermann's formula
- Proof of the existence of an eigenvalue over an algebraically closed field
- Strang splitting
- Proof of the variation of constants formula for linear systems
- Zermelo's navigation problem
- Lie–Trotter product formula
- Routh–Hurwitz stability criterion
- Regular value theorem
- Proof of the determinant of the inverse
- Inverse function theorem in Banach spaces
- Proof of the inverse function theorem by the contraction mapping principle
- Kharitonov's theorem
- Proof of the polar decomposition from the singular value decomposition
- Born rule
- Borel functional calculus
- Proof of the matrix determinant lemma from Sylvester's determinant theorem
- Proof of the formula for the determinant of a 2 by 2 matrix
- Proof of the Cholesky decomposition by induction on the size
- Configuration space
- Schmidt decomposition
- Hyperbolic set
- Operator monotone function
- Proof of the spectral theorem for normal matrices by deflation
- Mercer's theorem
- Proof of the spectral theorem for Hermitian matrices
- Lagrange multipliers for constraints
- Proof that the minimal polynomial divides the characteristic polynomial
- Proof of triangularisation by induction on the size
- Proof of Sylvester's determinant theorem by two block factorizations
- Proof of the product of a matrix and its adjugate by Laplace expansion
- Anharmonic oscillator
- Proof of the volume of a ball in R^3 from the n-dimensional formula
- Generalized Lotka–Volterra equation
- Proof of the determinant of a triangular matrix by the Leibniz formula
- Quantum computing
- Wave function collapse
- Principal component analysis
- Proof of the Leibniz formula from the defining properties of the determinant
- Proof of the Cayley–Hamilton theorem for linear maps
- Axiom A
- Inertia tensor and principal axes
- Bidiagonalization
- Pole placement theorem
- Duffing equation
- Kapitza's pendulum
- Liénard–Chipart criterion
- Indirect utility function
- Proof of the Vandermonde determinant by column operations
- Schur product theorem
- Singular values of a compact operator
- Numerical methods for linear least squares
- Spherical pendulum
- Observable
- Slice theorem
- Schmidt's singular value decomposition of a kernel
- Proof that the determinant of a matrix exponential is the exponential of the trace
- Proof that the eigenvalues are the roots of the characteristic polynomial
- Van der Pol oscillator
- Proof of the rule of Sarrus
- Polar decomposition of the deformation gradient
- Anosov diffeomorphism
- Spectral theorem for bounded normal operators
- Proof of the Cauchy–Binet formula by multilinearity
- Adjoint state method
- Stability conjecture
- Hidden-variable theory
- Channel capacity of a quantum channel
- Stabilizability
- Gain scheduling
- Proof of the Cayley–Hamilton theorem with the adjugate
- Amitsur–Levitzki theorem
- Hill differential equation
- Proof that the determinant of a linear map does not depend on the basis
- Time-optimal control
- Proof that the determinant is the product of the eigenvalues by comparing constant terms
- Normal form
- Proof of the QR decomposition by clearing the first column
- Proof that similar matrices have the same characteristic polynomial
Further reading
- Web https://en.wikipedia.org/wiki/Determinant, As an alternating multilinear form
About this page
| Tag | KZQQBSRJMS |
|---|---|
| URI | m2://KZQQBSRJMS |
| Kind | proof |
| Writing | W0 stub |
| MSC | 15A15 |
| Proves | Determinant of the identity matrix |
| Uses | Determinant, Identity matrix |
| Changed | 4 November 2026 |
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