PDF p. 20 (printed p. 14) — the symmetric price is lower with network effects iff e > e_p = 2(t − μ)

Let $t>0$ and $0<\mu<t$, and let $p^M(\mu)=(t-\mu)(\mu+e)/(2t-\mu)$ be the symmetric partial-multihoming price (26), so that without network effects $p^M(0)=e/2$. With the price threshold $e_p\equiv 2(t-\mu)$,

This is the price half of Proposition 2: network effects lower the price exactly when the goods have many exclusive features.

Formalization Note The paper's sentence states the direction "$e>e_p \Rightarrow$ lower"; the equivalence is the form the paper's own computation gives and is posed here. Network effects are strict, $\mu>0$; at $\mu=0$ both prices coincide.