We suggest reducing the design matrix to row echelon form as a means of finding the structure of all estimable functions. We illustrate the procedure with two examples.

Let Ω ⊂ ℝp, p ϵ ℕ* be a nonempty subset and B (Ω) be the Branch lattice of all bounded real functions on a Ω, equipped with sup norm. Let 𝑋 ⊂ 𝐵 (Ω) be a linear sublattice of 𝐵 (Ω) and 𝐴: 𝑋 → 𝑋 ...