Math Problem Statement

Suppose 𝑣1 , … , π‘£π‘š is a list of vectors in 𝑉. Define 𝑇 ∈ β„’(𝐅 π‘š, 𝑉) by 𝑇(𝑧1 , …, π‘§π‘š) = 𝑧1𝑣1 + β‹― + π‘§π‘šπ‘£π‘š. (a) What property of 𝑇 corresponds to 𝑣1 , … , π‘£π‘š spanning 𝑉?

Solution

The linear map T∈L(Fm,V)T \in \mathcal{L}(\mathbb{F}^m, V) is defined by

T(z1,…,zm)=z1v1+β‹―+zmvmT(z_1, \dots, z_m) = z_1v_1 + \dots + z_mv_m

where z1,…,zm∈Fz_1, \dots, z_m \in \mathbb{F} are scalars, and v1,…,vm∈Vv_1, \dots, v_m \in V are vectors in a vector space VV.

(a) What property of TT corresponds to v1,…,vmv_1, \dots, v_m spanning VV?

The property of TT that corresponds to the vectors v1,…,vmv_1, \dots, v_m spanning VV is that TT is surjective (or onto).

Explanation:

  • A set of vectors v1,…,vmv_1, \dots, v_m spans the vector space VV if every vector in VV can be written as a linear combination of v1,…,vmv_1, \dots, v_m.
  • This means for every v∈Vv \in V, there exists a tuple (z1,…,zm)∈Fm(z_1, \dots, z_m) \in \mathbb{F}^m such that: v=z1v1+β‹―+zmvm=T(z1,…,zm)v = z_1v_1 + \dots + z_mv_m = T(z_1, \dots, z_m)
  • Hence, the condition that v1,…,vmv_1, \dots, v_m span VV is equivalent to saying that TT is surjective. In other words, the image of TT covers the entire space VV, meaning Im(T)=V\text{Im}(T) = V.

Would you like further details on the concept of surjectivity or how it's proven in this context?

Here are 5 related questions to think about:

  1. What does it mean for TT to be injective in this context?
  2. How does the dimension of Fm\mathbb{F}^m relate to the dimension of VV when TT is surjective?
  3. What happens if v1,…,vmv_1, \dots, v_m are linearly dependent?
  4. Can the vectors v1,…,vmv_1, \dots, v_m span VV if m<dim⁑(V)m < \dim(V)?
  5. How would you describe the kernel of TT when v1,…,vmv_1, \dots, v_m span VV?

Tip: Surjectivity means that for every element in the codomain, there is a preimage in the domain. This is crucial for spanning sets, as they need to cover the entire space.

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Math Problem Analysis

Mathematical Concepts

Linear Algebra
Vector Spaces
Linear Maps
Span

Formulas

T(z1, ..., zm) = z1v1 + ... + zmvm

Theorems

Surjectivity of a Linear Map
Spanning Set Theorem

Suitable Grade Level

Undergraduate