Functional Equations and information theory: $f(xy)=f(x)f(y)$ for all $x,y\in[0,1]$
13086
Overview of basic facts about Cauchy functional equation
26183
Prob. 9, Sec. 4.3 in Kreyszig's Functional Analysis Book: Proof of the Hahn Banach Theorem without Zorn's Lemma
409
functions satisfying $f(x - y) = f(x) f(y) - f(a - x) f(a + y)$ and $f(0)=1$
136475
d'Alembert-like functional equation: $f(x+y)+g(x-y)=\lambda f(x)g(y)$
20568
Does the following have a solution for f(x,y)?
27809
Find the function equation $f(x+f(y)+yf(x))=y+f(x)+xf(y)$
108329
If $T\alpha=c\alpha$, then there is a non-zero linear functional $f$ on $V$ such that $T^{t}f=cf$
21891
If $f(xy)=f(x)f(y)$ then show that $f(x) = x^t$ for some t
25654
E[X| X>Y] for independent X, Y ~ N(0,1)
90435
Prove that there exist linear functionals $L_1, L_2$ on $X$
32432
Strategies to find the set of functions $f:\mathbb R\to\mathbb R$ satisfing the functional equation: $f(x^3)+f(y^3)=(x+y)(f(x^2)+f(y^2)-f(xy))$
131586
Hard functional equation: $ f \big ( x y + f ( x ) \big) = f \big( f ( x ) f ( y ) \big) + x $
88311
Linear functional f(v)=0 imply v=0
125788
A function with a property $f(x+y)=f(x)f(y)$
85282
Will inverse functions, and functions always meet at the line $y=x$?
71049
Functional equation $f(xy)=f(x)+f(y)$ and continuity
144557
Linearly independent functionals