is T, near the identity, invertible?
52791
Invertibility of an operator $T$ if $\|I-T\|<1$
131701
Why is $A^TA$ invertible if $A$ has independent columns?
77891
$(U\circ T)^{*} = T^{*}\circ U^{*}$
101320
How to tell $i$ from $-i$?
7034
Prove that $A+I$ is invertible if $A$ is nilpotent
33396
Generalizing a Trig Identity
5758
Prove that $I+\lambda A$,$I+\lambda B$,$I+\lambda C$ are invertible and A=B=C
106398
If $A$ is invertible show that $\det(A) \neq 0$
67208
Can we say that there exist an integer $n$ such $A+nB$ invertible?
140190
Binary operation $xy$, has identity, but not associativity. Is the inverse unique?
15793
Is the formula $(\text{ker }A)^\perp=\text{im }A^T$ necessarily true?
76674
Let $S:U\rightarrow V, \ T:V\rightarrow W$ and if $S$ and $T$ are both injective/surjective, is $T\circ S$ injective/surjective?
6398
Can the product of an $4\times 3$ matrix and a $3\times 4$ matrix be invertible?
63475
Is there any connection between a matrix being invertible and being diagonalizable?
148946
If $\mathbf{A}$ is a $2\times 2$ matrix that satisfies $\mathbf{A}^2 - 4\mathbf{A} - 7\mathbf{I} = \mathbf{0}$, then $\mathbf{A}$ is invertible
112707
Must $Q^\mathsf{T}Q = I$ if $(Qx)^\mathsf{T}(Qx) = x^\mathsf{T}x$
144019
A strictly positive operator is invertible