<<< native [ EUnderover False (EIdentifier "BASE") (EIdentifier "s") (EIdentifier "t") , ESymbol Rel "=" , EUnderover False (EIdentifier "BASE") (EGrouped [ EPhantom (ENumber "1") , EIdentifier "s" , EPhantom (ENumber "1") ]) (EGrouped [ EPhantom (ENumber "1") , EIdentifier "t" , EPhantom (ENumber "1") ]) ] >>> mml $$\underset{s}{\overset{t}{\mathrm{BASE}}}=\underset{\phantom{1}s\phantom{1}}{\overset{\phantom{1}t\phantom{1}}{\mathrm{BASE}}}$$