Linear independence #
This file collects consequences of linear (in)dependence and includes specialized tests for specific families of vectors, requiring more theory to state.
Main statements #
We prove several specialized tests for linear independence of families of vectors and of sets of vectors.
linearIndependent_option,linearIndependent_fin_cons,linearIndependent_fin_succ: type-specific tests for linear independence of families of vector fields;linearIndependent_insert,linearIndependent_pair: linear independence tests for set operations
In many cases we additionally provide dot-style operations (e.g., LinearIndependent.union) to
make the linear independence tests usable as hv.insert ha etc.
We also prove that, when working over a division ring, any family of vectors includes a linear independent subfamily spanning the same subspace.
TODO #
Rework proofs to hold in semirings, by avoiding the path through
ker (Finsupp.linearCombination R v) = ⊥.
Tags #
linearly dependent, linear dependence, linearly independent, linear independence
A finite family of vectors v i is linear independent iff the linear map that sends
c : ι → R to ∑ i, c i • v i is injective.
See also iSupIndep_iff_linearIndependent_of_ne_zero.
TODO : refactor to use Maximal.
A finite family of vectors v i is linear independent iff the linear map that sends
c : ι → R to ∑ i, c i • v i has the trivial kernel.
Also see LinearIndependent.pair_iff' for a simpler version over fields.
Properties which require DivisionRing K #
These can be considered generalizations of properties of linear independence in vector spaces.
A shortcut to a convenient form for the negation in LinearIndepOn.mem_span_iff.
Alias of LinearIndepOn.notMem_span_iff.
A shortcut to a convenient form for the negation in LinearIndepOn.mem_span_iff.
Alias of LinearIndepOn.notMem_span_iff_id.
LinearIndepOn.pair_iff is a version that works over arbitrary rings.
Also see LinearIndependent.pair_iff for the version over arbitrary rings.
See LinearIndependent.fin_cons' for an uglier version that works if you
only have a module over a semiring.
Equivalence between k + 1 vectors of length n and k vectors of length n along with a
vector in the complement of their span.
Equations
- One or more equations did not get rendered due to their size.
Instances For
Indexed version of exists_linearIndependent.
LinearIndepOn.extend adds vectors to a linear independent set s ⊆ t until it spans
all elements of t.
Equations
- hs.extend hst = Classical.choose ⋯