18. A ternary code (one whose alphabet size is three) C is

{cbaaa,bcabc,bacbc,aabbc,acccb,cbbab}.

Verify that d(C) = 2, so that by Theorem 2.2 C is not 1 error-correcting.

However, this only means that nearest neighbour decoding will not correet

alt instances of words received with one error. Find examples of words received with one error which:

(a) are correctly decoded;

(b) are incorreetly decoded.