The curried version of let f (x,y,z) = (x,(y,z)) is
let f (x,(y,z)) = (x,(y,z))
Just f (because f is already curried)
let f x y z = (x,(y,z))
let f x y z = x (y z)
5. Let X, Y and Z be sets. Let f : X ! Y and g : Y ! Z
functions.
(a) (3 Pts.) Show that if g f is an injective function, then f
is an injective function.
(b) (2 Pts.) Find examples of sets X, Y and Z and functions f
: X ! Y and g : Y ! Z such that g f is
injective but g is not injective.
(c) (3 Pts.) Show that if...
Let X and Y be independent and identical uniform distribution on
[0, 1]. Let Z=min(X, Y). Find E[Y-Z].
Hint: condition on whether Y=Z or not. What is the probability
Y=Z?
Let f(x,y) be a scalar function, and let F(x,y,z) be a vector
field. Only one of the following expressions is meaningful. Which
one?
a) grad f x div F
b) div(curl(grad f))
c) div(div F)
d) curl(div(grad f))
e) grad(curl F)
Let X and Y be independent positive random variables. Let Z=X/Y.
In what follows, all occurrences of x, y, z are assumed to be
positive numbers.
Suppose that X and Y are discrete, with known PMFs, pX and pY.
Then,
pZ|Y(z|y)=pX(?).
What is the argument in the place of the question mark?
Suppose that X and Y are continuous, with known PDFs, fX and fY.
Provide a formula, analogous to the one in part (a), for fZ|Y(z|y)
in terms...
Given a function φ(z) with z = x+iy let
U(x, y) = ½ [φ(x+iy) + φ(x-iy)] and V(x, y) = i/2
[φ(x+iy) –φ(x-iy)]
A) For φ(z) = z2 find U and V and their induced
vector fields E =▼U and
F =▼V also show that ▼2U =
▼2V = 0
B) Repeat for f(z) = z3
C) For f(z) = ln z we get U(x, y) = ½ ln
(x2+y2) and V(x, y) = arctan (y/x) Find ▼U
(electrostatic...
Prove Proposition 6.10 (Let f : X → Y and g : Y → Z be one
to one and onto functions. Then g ◦ f : X → Z is one to one and
onto; and (g ◦ f)−1 = f−1 ◦ g−1
).
3. Let F : X → Y and G: Y → Z be functions.
i. If G ◦ F is injective, then F is injective.
ii. If G ◦ F is surjective, then G is surjective.
iii. If G ◦ F is constant, then F is constant or G is
constant.
iv. If F is constant or G is constant, then G ◦ F is
constant.