Abstract:
It is proved that every two $\Sigma$-presentations of an ordered field $\mathbb R$ of reals
over $\mathbb{HF(R)}$, whose universes are subsets of $\mathbb R$, are mutually $\Sigma$-isomorphic. As
a consequence, for a series of functions $f\colon\mathbb R\to\mathbb R$ (e.g., $\exp$, $\sin$, $\cos$, $\ln$), it is stated that the structure $\mathbb R=\langle R,+,\times,<,0,1,f\rangle$ lacks such $\Sigma$-presentations
over $\mathbb{HF(R)}$.
Keywords:$\Sigma$-presentation, ordered field of reals.