 We can look at what is roughly speaking a mirror-image of the Tonk example to reinforce the contrast between Cut-inductivity and Id-inductivity and their respective links with existence and uniqueness, and then sort out the “roughly speaking” part of this description, which will show them as providing, rather, special—one might say canonical—cases of the satisfaction of the existence ( = conservative extension) and uniqueness conditions. We conduct the discussion in Set-Set rather than Set-Fmla to avoid a mass of complications. The above Tonk rules combine a left insertion rule familiar from the sequent calculus treatment of ∧ and a right insertion rule familiar from that of ∨; their reformulation for the change of framework just announced requires an idle Δ parameter on the right of the sequents in the premisses and conclusions of the rules as schematically presented above (replacing the χ in the one case, accompanying the displayed succedent formulas in the other). For our mirror image  example,[31]  consider a binary connective Knot with rules combining instead the left insertion rule for ∨ with the right insertion rule for ∧: