Information Geometry and Complex Geometry: Gluing a Partial $\mathcal F$-completion in $n=2$
Consider a family of functions $$f_t(x) := e^{\frac{t}{\log x}}, \quad x \in (0,1), \quad t \in [1/2, 2],$$ each of which can be viewed as a smooth curve in the $(x, f)$-plane for fixed $t$. As $t$ varies, this defines a continuous family of curves, or equivalently, a surface embedded in the extended space $(x, f, t)$. We now define a topological gluing operation by identifying the boundary curves corresponding to $t = 1/2$ and $t = 2$ in the $(x, f)$-plane. The identification is performed along straight lines of slope $+1$, i.e., lines of the form $$f = x + b, \quad b \in [-1, 1].$$ Explicitly, we declare the point $(x, f_{1/2}(x))$ to be equivalent to $(x', f_2(x'))$ whenever both points lie on the same line of slope $+1$; that is, whenever $$f_{1/2}(x) - x = f_2(x') - x',$$ so that both have the same intercept $b \in [-1, 1]$. This identification defines an equivalence relation that glues the endpoints of the parameter domain $t \in [1/2, 2]$ together along a $1$-par...