Chapter 9Some Constructions of Cross-Over Designs
9.1 INTRODUCTION
The construction and looking into the existence or nonexistence of designs is as important as providing the analysis for a given class of designs. Finite geometries, methods of differences, patchwork methods, and recursive methods are commonly used procedures for constructing designs. In Section 9.2, a brief review of Galois fields (GF) is provided, and in subsequent sections, some construction methods of the previously introduced designs are considered.
9.2 GALOIS FIELDS
Given a set of elements, F, a system is said to be a field, if the following conditions are satisfied:
- a, b ∈ F ⇒ a + b ∈ F, a · b ∈ F.
- a + (b + c) = (a + b) + c, a · (b · c) = (a · b) · c.
- a + b = b + a, a · b = b · a.
- ∃0, such that a + 0 = a, ∃1, such that a · 1 = a.
- ∃ (-a), such that a + (-a) = 0.
- ∀ a ≠ 0, ∃ (a– 1), such that a · (a- 1) = 1.
- a · (b + c) = a · b + a · c.
The number of elements, s, in a field is finite if s is a prime or prime power. These elements are called Galois fields and are written as GF(s). The quantity a is said to be congruent to b modulus s and is written a ≡ b(mod s), iff, a – b is divisible by s. If s is a prime p, the set of integers {0, 1, …, p - 1} is a field if these are multiplied or added in the usual manner and are reduced by mod p. For example, with s = 5, a field of 5 elements is {0, 1, 2, ...
Get Repeated Measurements and Cross-Over Designs now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.