\[\xymatrix @R+1pc @C+2pc { ℂ \ar@{}[r]^(.20){}="a"^(.85){}="b" \ar@<-5pt>@{^{(}->}^{i} "a";"b" \ar@{}[d]^(.18){}="c"^(.85){}="d" \ar@<-3pt>@{^{(}->}_{\mathbf{y}_ℂ} "c";"d" & 𝔻 \ar[dl]^-{N_i} \\ \widehat{ℂ} & }\]