 To obtain a clearer overview of these relations, let us introduce some notation and once again use the language of set theory. We will use bold letters to symbolize sets of items (propositions or variable ideas). Thus, for instance, ‘\(\mathbf{A(i)}\)’ and ‘\(\mathbf{M(i)}\)’ will be used to represent sets of propositions \(\mathbf{A}=\{A, B, C, \ldots\}\) and \(\mathbf{M}=\{M, N, O, \ldots\}\) in which the ideas \(\mathbf{i}=i, j, k, \ldots\) are considered variable. Let \(\mathbf{V(A(i))}\) represent the set of verifying ideas for \(\mathbf{A(i)}\). Finally, let \(\mathbf{\neg A}\) represent \(\{\neg A, \neg B, \neg C, \ldots\}\). We then have: