... one has a1 b1 + a2 b2 + a3 b3 + a4 b4 = {a1 b1 + a2 b2 } + {a3 b3 + a4 b4 } 1 1 ≤ (a2 + a2 ) (b2 + b2 ) + (a2 + a2 ) (b2 + b2 ) 2 4 1 ≤ (a2 + a2 + a2 + a2 ) (b2 + b2 + b2 + b2 ) , 4 which is ... α+β α+β (2. 26) and, for a typical corollary, show that one also has the more timely bound x2004 y + xy 20 04 ≤ x2005 + y 20 05 Exercise 2. 4 (A Canadian Challenge) Participants in the 20 02 Canadian ... to 2k The average A is listed 2k − n times in the padded sequence {αi }, so, when we apply inequality (2. 5) to {αi }, we find 2k −n a1 a2 · · · an ·A 1/2k ≤ a1 + a2 + · · · + an + (2k − n)A 2k...
... (x + y + z) ≤ x2 + y + (b) Show for < x ≤ y ≤ z that √ y2 + z2 ≤ x + y2 + z2 + x2 + z (y − x )2 + (z − x )2 (c) Show for positive x, y, z that √ ≤ x2 + y + z + x 2 + y 2 + z 2 This list can ... centered at the origin Fig 4.1 This arrangement of = 22 + circles in [ 2, 2] 2 has a natural generalization to an arrangement of 2d + spheres in [ 2, 2] d This general arrangement then provokes a question ... inequality Problem 4 .2 (Triangle Inequality for Euclidean Distance) Show that the function ρ : Rd × Rd → R defined by ρ(x, y) = (y1 − x1 )2 + (y2 − x2 )2 + · · · + (yd − xd )2 (4 .2) satisfies the triangle...
... numbers a1 , a2 , b1 , and b2 satisfy max{a1 , a2 } ≥ max{b1 , b2 } and a1 + a2 = b1 + b2 , then for nonnegative x and y, one has xb1 y b2 + xb2 y b1 ≤ xa1 y a2 + xa2 y a1 (5 .22 ) Prove this ... a2 and b1 ≤ b2 imply ≤ (a2 − a1 )(b2 − b1 ), and when this is unwrapped, we find a1 b2 + a2 b1 ≤ a1 b1 + a2 b2 , Consequences of Order 79 which is precisely the rearrangement inequality (5. 12) ... Show that if < m = x1 ≤ x2 ≤ · · · ≤ xn = M < ∞ then for nonnegative weights with p1 + p2 + · · · + pn = one has n n pj xj j=1 pj j=1 xj ≤ 22 (5 .21 ) √ where µ = (m + M ) /2 and γ = mM This bound...
... implies the area formula a2 = (b − c )2 + 4A tan(α /2) , then show how Jensen’s inequality implies that in any triangle one has √ a2 + b2 + c2 ≥ (a − b )2 + (b − c )2 + (c − a )2 + 3A This bound is known ... bound M x2 − f (¯) ≤ ¯ x n pk k=1 M x2 − f (xk ) k where we have set x = p1 x1 + p2 x2 + · · · + pn xn , and this bound is easily ¯ rearranged to yield n pk f (xk ) −f (¯) ≤ x k=1 M n pk x2 − 2 x ... log 2) visible, the graph is not drawn to scale.) convexity properties of f , so we just differentiate twice to find f (x) = − ex 2( 1 + ex )3 /2 and f (x) = − (1 + ex )−3 /2 ex + (1 + ex )−5 /2 e2x...
... note that for any ≤ t < ∞ we have t t f (t)t2α+1 − x2α+1 f (x) dx 2 + 2 + t f (t)t2α+1 + x2α+1 |f (x)| dx = 2 + 2 + t x2α+1 |f (x)| dx ≥ 2 + x2α f (x) dx = (7.8) By the hypothesis (7.7) ... to the splitting xα+β+1 |f (x)| = {x (2 +1) /2 |f (x)|1 /2 } {x (2 +1) /2 |f (x)|1 /2 } we find the nice intermediate bound ∞ (1 + α + β )2 I ≤ ∞ x2α+1 |f (x)| dx x2β+1 |f (x)| dx Now we see how we can ... h such that h ≤ f (x)/D(x) one has h F (x) ≥ h u2 |f (u) |2 du = (x + t )2 |f (x + t) |2 dt h (x + t )2 |f (x) − t D(x) |2 dt ≥ ≥ hx2 {f (x) − h D(x) }2 , or, a bit more simply, we have 1 F (x) ≥ h...
... Means 129 Problem 8.4 (Termwise Bounds for Carleman’s Summands) Show that for positive real numbers ak , k = 1, 2, , one has (a1 a2 · · · an )1/n ≤ e 2n2 n (2k − 1)ak for n = 1, 2, , (8 .22 ) ... (ny) dy = yak dy = k=1 (k−1)/n 2n2 n (2k − 1)ak , (8 .26 ) k=1 so, in view of the general bound (8 .25 ) and the identity (8 .23 ), the proof of the first inequality (8 .22 ) of the challenge problem is ... Exercise 8 .2 (Harmonic Means and Recognizable Sums) Suppose x1 , x2 , , xn are positive and let S denote their sum Show that we have the bound S n2 S S ≤ + + ··· + (2n − 1) 2S − x1 2S − x2 2S −...
... convex φ and positive weights w1 , w2 , , wn one has φ w1 x1 + w2 x2 + · · · + wn xn w1 + w2 + · · · + wn w1 φ(x1 ) + w2 φ(x2 ) + · · · + wn φ(xn ) ≤ w1 + w2 + · · · + wn (9.31) Consider the ... real root of the 146 H¨lder’s Inequality o equation n n p /2 aj nλ − 2 p 1−p +n aj j=1 = (9 .22 ) j=1 Since a quadratic equation A 2 + 2Bλ + C = has a real root if and only if AC ≤ B , we see that ... inequality which he wrote in the form w1 +w2 +···+wn w1 x1 + w2 x2 + · · · + wn xn w1 + w2 + · · · + wn xw1 xw2 · · · xwn ≤ n where the values w1 , w2 , ,wn are assumed to be positive but which...
... (t) k k=1 a2 k =2 k=1 n k a2 k k=1 Hilbert’s Inequality and Compensating Difficulties 165 (c) Combine the preceding observations to conclude that n n ≤ 2 ak n a2 k k=1 k=1 k a2 k (10 .24 ) k=1 This ... Compensating Difficulties In the specific case of f (x) = m2λ x2λ (m + x)−1 , we therefore find ∞ m m+n n n=1 ∞ 2 ≤ m2λ dx = m + x x2λ ∞ 1 dy, (10.6) (1 + y) y 2 where the last equality comes from the change ... (10 .2) to the pair (10.4), we find ∞ ∞ am bn m+n m=1 n=1 ∞ ∞ ≤ a2 m m m+n n m=1 n=1 2 ∞ ∞ b2 n n m+n m n=1 m=1 2 , so, when we consider the first factor on the right-hand side we see ∞ ∞ m a2 m...
... a2 − sN +1 (a1 + a2 + · · · + an )2 + sn 2( a1 + a2 + · · · + an−1 )an + a2 n n =2 and, since sN +1 (a1 + a2 + · · · + an )2 ≥ 0, we at last find N n=1 (a1 + a2 + · · · + an ) n N 2 sn (a1 + a2 ... “humble bound” and note that if we replace An An−1 by (A2 + A2 ) /2 we have n n−1 ∆n ≤ (1 − 2n)A2 + (n − 1) A2 + A2 n n n−1 = (n − 1)A2 − nA2 n−1 n After a few dark moments, we now find that we ... now try to write ∆n just in 1 72 Hardy’s Inequality and the Flop terms of An and An−1 , then we have ∆n = A2 − 2An an n = A2 − 2An nAn − (n − 1)An−1 n = (1 − 2n)A2 + 2( n − 1)An An−1 , n but unfortunately...
... we just take α = (α1 , 2 ) = (ρ + σ, ρ − σ) and take β = (β1 , 2 ) = (ρ + τ, ρ − τ ) There is no loss of generality in assuming α1 ≥ 2 , β1 ≥ 2 , and α1 + 2 = β1 + 2 ; moreover, no loss in ... such that max(x1 , x2 , , xn ) ≤ (x1 + x2 + · · · + xn )/k, show that one has n j=1 k2 ≤ (n − k) + + xj k + x1 + x2 + · · · + xn (13 .21 ) Majorization and Schur Convexity 20 5 Exercise 13.3 (A ... numbers x1 , x2 , , xn such that m xk = k=1 m n n xk + δ (13 .22 ) k=1 where δ ≥ 0, show that the sum of squares has the lower bound n x2 ≥ k k=1 n n xk + k=1 δ2n m(n − m) (13 .23 ) This refinement...
... Random Variables 199 20 3 21 0 21 2 21 6 21 8 22 1 22 6 23 5 Chapter Random Matrices 9.1 Linearity of Expected Values 9 .2 Means and Variances of Quadratic Forms in Random Matrices 24 5 24 5 24 9 Chapter 10 The ... Chapter 22 Specific Datasets 563 x CONTENTS 22 .1 22 .2 22. 3 22 .4 22 .5 Cobb Douglas Aggregate Production Function Houthakker’s Data Long Term Data about US Economy Dougherty Data Wage Data 563 580 5 92 ... element only, and ∅ for the empty set ∞ (2. 2.9) n=1 ∞ (2. 2.10) n=1 ∞ ,2 = n ,2 = n 0, = n 0, + = n n=1 ∞ n=1 Answer ∞ ,2 n (2. 2.11) , = (0, 2] n (2. 2. 12) n=1 ∞ 0, n =∅ 0, + n = [0, 1] n=1 n=1...