On the relation between finitely and infinitely repeated games with incomplete information

For a class of repeated two-person zero-sum games with incomplete information it was proved byAumann andMaschler that \(\mathop {\lim }\limits_{n \to \infty } v_n\) exists,Ν _n being the value of the game withn repetitions. As for the speed of convergenceAumann andMaschler showed that the error termδ _n=¦Ν _n?limΝ _n¦ is bounded from above byc/√n for some positive constantc. Both results have been generalized byMertens andZamir. It is shown in this paper that the above mentioned theorem about the speed of convergence is sharp in the sense that there are games in whichδ _n≥c′/√n for some positive constantc′. However there are games for which δ_n is of a lower order of magnitude, for instancec′(logn)/n≤δ _n≤c (logn)/n orc′/n≤δ _n≤c/n. Sufficient conditions are given here for games to belong to one of these categories as well as examples of games from each category.     

ψ-Stability of a cooperative game without side payments

In the present paper we defineψ-stability for theAumann-Peleg theory of cooperative games without side payments, and we prove some theorems which are analogous to the core theorem byAumann andBurger. These theorems provide foundations of the theory ofψ-stability for cooperative games without side payments in addition to being of interest for their own sake. We also consider the composition of two admissible functionsψ ₁ andψ ₂.     

Values of mixed games

Aumann andShapley [1973] have investigated values of games in which all players are individually insignificant, i.e. form a non-atomic continuum, or “ocean”. In this paper we treat games in which, in addition to such an ocean, there are also some “atoms”, i.e. players who are individually significant. We define spaces of such games that are analogous to those investigated byAumann andShapley, and prove the existence of values on some of them. Unlike in the non-atomic case, we find that in general there are infinitely many values, corresponding to various ways in which the atoms can be imbedded in the ocean. The results generalize those ofMilnor andShapley [1961]. Precise statements will be found in Section 2.     

Constrainedn-person games

The usual properties of a characteristic function game were derived byvon Neumann andMorgenstern from the properties of a game in normal form. In this paper we give a linear programming principle for the calculation of the characteristic function. The principle is a direct application ofCharnes' linear programming method for the calculation of the optimal strategies and the value of a two-person zero-sum game. The linear programming principle gives another method for proving the standard properties of a characteristic function when it is derived from a game in normal form. Using an idea originated byCharnes for two person games, we develop the concept of a constrainedn-person game as a simple, practical extension of ann-person game. However the characteristic function for a constrainedn-person game may not satisfy properties, such as superadditivity, usually associated with a characteristic function.     

Zero-sum sequential games with incomplete information

Repeated zero-sum two-person games of incomplete information on one side are considered. If the one-shot game is played sequentially, the informed player moving first, it is proved that the value of then-shot game is constant inn and is equal to the concavification of the game in which the informed player disregards his extra information. This is a strengthening ofAumann andMaschler's results for simultaneous games. Optimal strategies for both players are constructed explicitly.     

Generalized impartial games

A complete mathematical theory of NIM type games have been developed byBouton [1902],Sprague [1935/36] andGrundy [1939]. The NIM type games are a special class of combinatorial games, called the impartial games. “Impartial” means that, at any stage, the set of legal moves is independent of whose turn it is to move. The outcome of an impartial game is that the first player either wins or loses. The results ofBouton, Sprague andGrundy are now generalized to a wider class of games which allow tie-positions. This wider class of games are defined on digraphs. It is proved that the games defined on a given digraph are all impartial games (without tie-positions) iff the birthday function (also called the terminal distance function) exists on this digraph.     

Values of games without side payments

A value forn-person games without side payments is given which coincides with theShapley value for games with side payments, and with theNash value for two-person games.     

On optimal backward perturbation bounds for the linear least squares problem

Consider the linear least squares problem min _x ‖b?Ax‖₂ whereA is anm×n (m<n) matrix, andb is anm-dimensional vector. Lety be ann-dimensional vector, and let ηls(y) be the optimal backward perturbation bound defined by $$\eta _{LS} (y) = \inf \{ ||F||_F :y is a solution to \mathop {min}\limits_x ||b - (A + F)x||_2 \} .$$ . An explicit expression of ηls(y) (y≠0) has been given in [8]. However, if we define the optimal backward perturbation bounds ηmls(y) by $$\eta _{MLS} (y) = \inf \{ ||F||_F :y is the minimum 2 - norm solution to \mathop {min}\limits_x ||b - (A + F)x||_2 \} ,$$ , it may well be asked: How to derive an explicit expression of ηmls(y)? This note gives an answer. The main result is: Ifb≠0 andy≠0, then ηmls(y)=ηls (y).     

Minmax and maxmin of repeated games with incomplete information

For a class of 2-Person 0-sum repeated games with incomplete information,Aumann/Masch1er [1967] andStearns [1967] have given a necessary and sufficient condition for the existence of v_∞ (the value of the infinitely repeated game).Mertens/Zamir [1971] andMertens [1971/72] have given the formula (and thus proved the existence) of \(\mathop {\lim }\limits_{n \to \infty } \) v _n , the limit of the values of the games withn repetitions, for a much larger class of games than that treated byAumann/Maschler andSteams. In this paper we extend the Aumann-Maschler-Stearns results to the larger family of games studied byMertens [1971/72].     

Factorization of Lipschitz functions and absolute convergence of Vilenkin-Fourier series

LetG be a Vilenkin group (i.e., an infinite, compact, metrizable, zero-dimensional Abelian group). Our main result is a factorization theorem for functions in the Lipschitz spaces \(\mathfrak{L}\mathfrak{i}\mathfrak{p}\) (α,p; G). As colloraries of this theorem, we obtain (i) an extension of a factorization theorem ofY. Uno; (ii) a convolution formula which says that \(\mathfrak{L}\mathfrak{i}\mathfrak{p} (\alpha , r; G) = \mathfrak{L}\mathfrak{i}\mathfrak{p} (\beta , l; G)*\mathfrak{L}\mathfrak{i}\mathfrak{p} (\alpha - \beta , r; G)\) for 0<β<α<∞ and 1≤r≤∞; and (iii) an analogue, valid for allG, of a classical theorem ofHardy andLittlewood. We also present several results on absolute convergence of Fourier series defined onG, extending a theorem ofC. W. Onneweer and four results ofN. Ja. Vilenkin andA. I. Rubinshtein. The fourVilenkin-Rubinshtein results are analogues of classical theorems due, respectively, toO. Szász, S. B. Bernshtein, A. Zygmund, andG. G. Lorentz.     

Kantorovič operators of second order

The Kantorovi? operators of second order are introduced byQ _n f= =(B _n+2 F)″ whereF is the double indefinite integraloff andB _n+2 the (n+2)-th Bernstein operator. The operatorsQ _n will reveal a close affinity to the so-called modified Bernstein operatorsC _n introduced bySchnabl [10] on a quite different way. The article contains investigations concerning the asymptotic behavior ofQ _n ^kn f (asn → ∞), where (k _n) is a sequence of natural numbers.     

On generalized quadratic equations in three prime variables

Leta ₁,a ₂ anda ₃ be any nonzero integers which are relatively prime and not all negative. In this paper, as a parallel problem of [11] for each integerk≥2, we consider the setE(X) of positive integersb≤X which satisfy the condition of congruent solubility and that the equation $$a_1 p_1^2 + a_2 p_2^2 + a_3 p_3^k = b$$ is insoluble in primesp _j. We obtain CardE(X)≤X ^1-ε. Our result extends the wellknown classical results (by Legendre and Gauss and byDavenport andHeilbronn [2]) on the equation $$x_1^2 + x_2^2 + x_3^k = b$$ in integral variablesx _j with the above bound for CardE(X) better than that in [2].     

Summability factors for lower-semi-matrix transformations

In view of Kogbetliantz's identity [7] the absolute Cesáro summability of orderk (k)>?1) of an infinite seriesΣ a _n is the same as the absolute convergence ofΣ(τ _n ^k )n ^?1 whereτ _n ^k is then-th Cesáro mean of orderk of sequence {na _n }.Das [5] has shown that similar dependence is true for certain classes of Nörlund means. The object of this paper is to establish two theorems on absolute summability factors involving two lower-semimatrix transformations and thereby to generalise a result ofChow [3] on absolute Cesáro summability factors and a result ofBosanquet andDas [1] on absolute Harmonic summability factors.     

A transplantation theorem for Fourier-Bessel coefficients

We prove a transplantation theorem for Fourier-Bessel coefficients. Theorems of such type were proved byAskey andWainger [1] andAskey [2] for ultraspherical and Jacobi coefficients, respectively. Our theorem can be also seen as a dual result to a transplantation theorem for Fourier-Bessel series which was proved byGilbert [3].     

Kombinatorische Beweise eines Satzes von Birman und Hilden und eines Satzes von Magnus mit der Theorie der automorphen Mengen und der zugehörigen Zopfgruppenoperationen

We deal with the well-known operation ofARTIN?S Braid GroupB _n on the free groupF _n by automorphisms, and give a proof for a theorem ofBIRMAN/HILDEN (here Satz B) by showing, that the images of the generators ofF _n underB _n are of a special form (Satz C). The theory ofBRIESKORN?S Automorphic Sets comes in here. With similar methods we give a proof of a theorem of Magnus saying thatB _n operates on a certain polynomial ring effectively by automorphisms (here Satz 9.2).     

The weighted Grammar constraint

We introduce the WeightedGrammar constraint and propose propagation algorithms based on the CYK parser and the Earley parser. We show that the traces of these algorithms can be encoded as a weighted negation normal form (WNNF), a generalization of NNF that allows nodes to carry weights. Based on this connection, we prove the correctness and complexity of these algorithms. Specifically, these algorithms enforce domain consistency on the WeightedGrammar constraint in time O(n ³). Further, we propose that the WNNF constraint can be decomposed into a set of primitive arithmetic constraint without hindering propagation.     

Bounded Degree, Triangle Avoidance Graph Games

We consider variants of the triangle-avoidance game first defined by Harary and rediscovered by Hajnal a few years later. A graph game begins with two players and an empty graph on n vertices. The two players take turns choosing edges within K _n , building up a simple graph. The edges must be chosen according to a set of restrictions ${\mathcal{R}}$ . The winner is the last player to choose an edge that does not violate any of the restrictions in ${\mathcal{R}}$ . For fixed n and ${\mathcal{R}}$ , one of the players has a winning strategy. For various games where ${\mathcal{R}}$ includes bounded degree and triangle avoidance, we determine the winner for all values of n.     

A generalization of the katona theorem for crosst-intersecting families

LetX be ann-element set and letA and? be families of subsets ofX. We say thatA and? are crosst-intersecting if |A ∩ B| ≥ t holds for all A ∈A and for allB ∈ ?. Suppose thatA and ? are crosst-intersecting. This paper first proves a crosst-intersecting version of Harper's Theorem:

1. There are two crosst-intersecting Hamming spheresA ₀,? ₀ with centerX such that |A| ≤ |A ₀| and|?| ≤ |? ₀| hold.
2. Suppose thatt ≥ 2 and that the pair of integers (|A) is maximal with respect to direct product ordering among pairs of crosst-intersecting families. Then,A and? are Hamming spheres with centerX.

Using these claims, the following conjecture of Frankl is proven:

1. Ifn + t = 2k ? 1 then |A| |?| ≤ max \(\left\{ {\left( {K_k^n + \left( {_{k - 1}^{n - 1} } \right)} \right)^2 ,K_k^n K_{k - 1}^n } \right\}\) holds, whereK _l ⁿ is defined as \(\left( {_n^n } \right)\left( {_{n - 1}^n } \right) + \cdots + \left( {_l^n } \right).\)
2. Ifn + t = 2k then |A| |? ≤ (K _k ⁿ )² holds.

The extremal configurations are also determined.     

On sums of graph games with last player losing

The purpose of this paper is to find the general class of graph games with last player losing which may be solved by an analogue ofBouton's [1901] solution. Moreover, it can be shown that this class contains all subtraction games, as well asLasker's [1931] nim and several other games. Games such asKayles andDawson's [1935] game with last player losing are not treated by the method of this paper and are still unsolved.     

On the Fourier transformation on spaces of (p,q)-multipliers

LetG denote a locally compact abelian topological group. The aim of the present paper is to prove an “intermediate” result between two well-known results ofL. Hörmander andG. I. Gaudry concerning the structure of the spaces ?_G?μ?t ^p,q (G).