| ⊦ gndx.nds = nd ' ↔ (∃ gnd. gndx = gnd ' ∧ gnd.nd = nd) |
∀ nd. gndx0.nds = nd ' ↔ (∃ gnd. gndx0 = gnd ' ∧ gnd.nd = nd) ⊦ (gnd + gndx0).nds = nd ' ↔ (∃ gnd0. gnd + gndx0 = gnd0 ' ∧ gnd0.nd = nd)
Used simplifier rules: nds-base: ⊦ [].nds = [];%group-node-list freely generated by [], +;;% ⊦ nd ' ≠ []; (s)% ⊦ gnd ' ≠ []; (s)