 For \(i = 1, 3\) or 4, \(\textrm{T}_i\) entails Co\(_i\). If No Twins is added to each theory, each \(\textrm{T}_i\) entails the principle which results from replacing ‘\(\phi\)’ by ‘\(F\)’ and ‘the set of all singletons’ by ‘\(W\)’ in Co\(_i\):