‎let $x$ be a real normed  space, then  $c(subseteq x)$  is  functionally  convex  (briefly, $f$-convex), if  $t(c)subseteq bbb r $ is  convex for all bounded linear transformations $tin b(x,r)$; and $k(subseteq x)$  is  functionally   closed (briefly, $f$-closed), if  $t(k)subseteq bbb r $ is  closed  for all bounded linear transformations $tin b(x,r)$. we improve the    krein-milman theorem  ...

We examine decision problems for various classes of convex languages, previously studied by Ang and Brzozowski under the name “continuous languages”. We can decide whether a language L is prefix-, suffix-, factor-, or subword-convex in polynomial time if L is represented by a DFA, but the problem is PSPACE-hard if L is represented by an NFA. If a regular language is not convex, we prove tight u...

L. Fejes Tóth [1] introduced the notion of fixing system for a compact, convex body M ⊂ Rn. Such a system F ⊂ bd M stabilizes M with respect to translations. In particular, every minimal fixing system F is primitive, i.e., no proper subset of F is a fixing system. In [2] lower and upper bounds for cardinalities of mimimal fixing systems are indicated. Here we give an improved lower bound and sh...

This is a survey of algorithmic results in the theory of “discrete convex analysis” for integer-valued functions defined on integer lattice points. The theory parallels the ordinary convex analysis, covering discrete analogues of the fundamental concepts such as conjugacy, the Fenchel min-max duality, and separation theorems. The technical development is based on matroid-theoretic concepts, in ...

Let H(k, l) denote the smallest integer such that any set of H(k, l) points in the plane, no three on a line, contains an empty convex k-gon and an empty convex l-gon, which are disjoint, that is, their convex hulls do not intersect. Hosono and Urabe [JCDCG, LNCS 3742, 117-122, 2004] proved that 12 ≤ H(4, 5) ≤ 14. Very recently, using a Ramsey-type result for disjoint empty convex polygons prov...

This paper uses convex bodies to study line bundles in the setting of Arakelov theory. The treatment is parallel to [Yu2], but the content is independent. The method of constructing a convex body in Euclidean space, now called “Okounkov body”, from a given algebraic linear series was due to Okounkov [Ok1, Ok2], and was explored systematically by Kaveh–Khovanskii [KK] and Lazarsfeld–Mustaţǎ [LM]...

In this note we show that a non-degenerated polytope in IRn with n+k, 1 ≤ k < n, vertices is far from any symmetric body. We provide the asymptotically sharp estimates for the asymmetry constant of such polytopes. 0 Introduction and notations The canonical Euclidean inner product in IR is denoted by 〈·, ·〉, the norm in `p is denoted by ‖ · ‖p, 1 ≤ p ≤ ∞. By a convex body K ⊂ IR we shall always ...

For one-dimensional system of dissipative balance laws endowed with a convex entropy we prove, under natural assumptions, that a constant equilibrium state is asymptotically L 2 ?stable under a zero-mass initial disturbance. The technique is based on the construction of an appropriate Liapunov functional involving the entropy and a so-called compensation term.

Spatial coupling has recently emerged as a powerful paradigm to construct graphical models that work well under low-complexity message-passing algorithms. Although much progress has been made on the analysis of spatially coupled models under message passing, there is still room for improvement, both in terms of simplifying existing proofs as well as in terms of proving additional properties. We...