WorldCat Identities

Balas, Egon

Overview
Works: 154 works in 317 publications in 4 languages and 1,952 library holdings
Genres: Conference papers and proceedings  Personal narratives  Biography  History 
Roles: Author, Editor, Honoree, Other
Classifications: DS135.R73, 519.77
Publication Timeline
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Most widely held works by Egon Balas
Integer programming and combinatorial optimization : 4th International IPCO Conference, Copenhagen, Denmark, May 29-31, 1995 : proceedings by Egon Balas( Book )

26 editions published in 1995 in English and held by 477 WorldCat member libraries worldwide

This volume constitutes the proceedings of the Fourth International Conference on Integer Programming and Combinatorial Optimization, IPCO '95, held in Copenhagen in May 1995 under the sponsorship of the Mathematical Programming Society. Integer programming and combinatorial optimization provide a fruitful theoretical and algorithmic basis for the solution of a number of optimization problems occuring in real-world situations, such as production planning and scheduling, routing, crew scheduling, or network construction. This volume presents 36 revised papers selected from a total of 105 submissions and offers a representative up-to-date snapshot on the state of the art in this interdisciplinary area of research and applications
Der Wille zur Freiheit : Eine gefährliche Reise durch Faschismus und Kommunismus by Egon Balas( )

5 editions published between 2011 and 2014 in German and held by 77 WorldCat member libraries worldwide

Wieviele Schritte muss ein Mensch gehen und wie gefährlich sind seine Wege, wieviel Leid erträgt ein Mensch und woher nimmt er die Kraft, um die einzige Bahn zu beschreiten, die für ihn wichtig ist: die zur Freiheit ohne Verlust seiner Rechtschaffenheit? Egon Balas erzählt in dieser ungemein fesselnd geschriebenen Autobiographie von den Wegen, die ihn aus Transsilvanien nach Pennsylvania führten, auf denen der 1922 in Klausenburg (Kolozsvár - ung., Cluj - rum.) geborene Sohn einer ungarisch-jüdischen Familie zum berühmten Mathematiker wurde, der seit 1966 in den USA lebt. Die Leser des Buches werden auf eine erstaunliche Lebensreise mitgenommen, sie erfahren von großem Mut und grenzenlosem Optimismus. Balas erlebte als Heranwachsender den Zusammenbruch der alten, vermeintlich sicheren Ordnung, schloss sich 1942 der Kommunistischen Partei Ungarns an, kämpfte im Untergrund gegen den Faschismus, wurde eingesperrt, gefoltert und konnte schließlich in den Kriegswirren fliehen. Mit seiner Geschichte gibt der Autor auch einen Einblick in die Tragödie der Siebenbürger Juden, deren Mehrzahl in den Jahren 1942-1944 ermordet wurde. Von den dreißig Mitgliedern der Balas-Familie überlebten nur sieben. Egon Balas' spätere Frau Edith gehörte zu den wenigen, die aus Auschwitz zurückkehrten. Nach dem Zweiten Weltkrieg hatte Balas infolge seines Widerstandes wichtige Funktionen im kommunistischen Rumänien inne. Er geriet zunehmend in Widerspruch zum stalinistischen Regime, saß als politischer Häftling mehr als zwei Jahre in Einzelhaft bei der rumänischen Staatssicherheit Securitate und kam erst nach Stalins Tod wieder frei. Wir erfahren in diesem spannenden Buch von den vielen überraschenden und unerwarteten Wendungen, die das ständige Auf und Ab eines aufregenden Lebens begleiten. Das Buch ist ein Tatsachenbericht, der sich wie ein Roman liest. Dabei wird der Leser auch in skurrile, in groteske Situationen einbezogen, die - nach beklemmenden S
Will to freedom : a perilous journey through fascism and communism by Egon Balas( Book )

9 editions published between 2000 and 2008 in English and French and held by 22 WorldCat member libraries worldwide

"A memoir of life under Nazi and communist rule in Hungary and Romania, this book provides an eyewitness account of the social and political upheaval that shook Eastern Europe from the mid-1930s to the mid-1960s. As an underground resistance fighter, political prisoner, fugitive, and Communist Party official, Egon Balas charts his journey from idealistic young Communist to disenchanted dissident."--Jacket
The perfectly matchable subgraph polytope of an arbitrary graph by Egon Balas( Book )

6 editions published in 1987 in English and German and held by 11 WorldCat member libraries worldwide

The Perfectly Matchable Subgraph Polytope of a graph G=(V, E), denoted by PMS (G) is the convex hull of the incidence vectors of those X is a subset of V which induce a subgraph having a perfect matching. A linear system is described, whose solution set is PMS (G), for a general (nonbipartite) graph G. It can be derived via a projection technique from Edmonds' characterization of the matching polytope of G. This system can be deduced from the earlier bipartite case, by using the Edmonds- Gallai structure theorem. Finally, we characterize which inequalities are facet inducing for PMS (G), and hence essential. Keywords Projection; Perfectly Matchable Subgraph Polytype; Polyhedral Combinatorics; Matching Theory
Combinatorial optimization by M. W Padberg( Book )

1 edition published in 1980 in English and held by 9 WorldCat member libraries worldwide

One machine scheduling with delayed precedence constraints by Egon Balas( Book )

4 editions published between 1992 and 1993 in English and held by 8 WorldCat member libraries worldwide

We study the one machine scheduling problem with release and delivery times and the minimum makespan objective, in the presence of constraints that for certain pairs of jobs require a delay between the completion of the first job and the start of the second (delayed precedence constraints). This problem arises naturally in the context of the Shifting Bottleneck Procedure for the general job shop scheduling problem, as a relaxation of the latter, tighter than the standard one machine relaxation. The paper first highlights the difference between the two relaxations through some relevant complexity results. Then it introduces a modified Longest Tail Heuristic whose analysis identifies those situations that permit efficient branching. As a result, an optimization algorithm is developed whose performance is comparable to that of the best algorithms for the standard one machine problem. Embedding this algorithm into a modified version of the Shifting Bottleneck Procedure that uses the tighter one machine relaxation discussed here results in a considerable overall improvement in performance on all classes of job shop scheduling problems
The perfectly matchable subgraph polytope of a bipartite graph by Egon Balas( Book )

7 editions published between 1981 and 1982 in English and German and held by 7 WorldCat member libraries worldwide

The following type of problem arises in practice: in a node-weighted graph G, find a minimum weight node set that satisfies certain conditions and, in addition, induces a perfectly matchable subgraph of G. This has led us to study the convex hull of incidence vectors of node sets that induce perfectly matchable subgraphs of a graph G, which we call the perfectly matchable subgraph polytype of G. For the case when G is bipartite, we give a linear characterization of this polytype, i.e., specify a system of linear inequalities whose basic solutions are the incidence vectors of perfectly matchable node sets of G. We derive this result by three different approaches, using linear programming duality, projection, and lattice polyhedra, respectively. The projection approach is used here for the first time as a proof method in polyhedral combinatorics, and seems to have many similar applications. Finally, we completely characterize the facets of our polytype, i.e., separate the essential inequalities of our linear defining system from the redundant ones. (Author)
DISJUNCTIVE PROGRAMMING by Egon Balas( Book )

6 editions published between 1974 and 2018 in English and held by 6 WorldCat member libraries worldwide

In this paper the author characterizes the convex hull of feasible points for a disjunctive program, a class of problems which subsumes pure and mixed integer programs and many other nonconvex programming problems. Two representations are given for the convex hull of feasible points, each of which provides linear programming equivalents of the disjunctive program. The first one involves a number of new variables proportional to the number of terms in the disjunctive normal form of the logical constraints; the second one involves only the original variables and the facets of the convex hull. Among other results, the author gives necessary and sufficient conditions for an inequality to define a facet of the convex hull of feasible points. (Modified author abstract)
A constraint-activating outer polar method for solving pure or mixed integer 0-1 programs by Egon Balas( Book )

3 editions published between 1972 and 1973 in English and held by 6 WorldCat member libraries worldwide

The paper discusses a procedure for solving pure and mixed integer 0-1 programs, based on the properties of outer polar sets introduced in another paper. Rather than generating cutting planes from outer polars, here the author uses the latter in a different way. Starting with a subset of the problem constraints, the author activates as many of the remaining constraints as are needed to produce a convex polytope that is contained in the outer polar of the convex hull of feasible integer points. When this is achieved, the algorithm terminates and the best solution found in the process is optimal. (Author)
Integer programming and convex analysis by Egon Balas( Book )

3 editions published in 1971 in English and held by 5 WorldCat member libraries worldwide

Convex analysis can be useful in integer programming as a means of generating information about the integer neighborhood of the linear programming optimum x, defined as the set of (integer) vertices of a unit cube K containing x. The first intersection cuts were based on information about the integer neighborhood within the cone defined by the problem constraints that are binding at x, while ignoring the non-binding constraints (except for those that define facets of K). This paper uses properties of polar sets to generate cuts based on information about the feasible integer neighborhood, i.e., about all problem constraints intersecting K. Cuts of this type can be gradually tightened by using information that is normally generated by almost any integer programming method; therefore they can be suitably combined with any implicit enumeration or branch and bound-type procedure. The results are valid for general pure or mixed integer programs, but they are expected to be most helpful in the (pure or mixed) 0-1 case. A combination of this approach with the asymptotic theory of integer programming is discussed. (Author)
On the set covering problem by Egon Balas( Book )

4 editions published between 1971 and 1973 in English and German and held by 5 WorldCat member libraries worldwide

Sequential Convexification in Reverse Convex and Disjunctive Programming by Egon Balas( Book )

3 editions published between 1986 and 1989 in English and held by 4 WorldCat member libraries worldwide

This paper is about a property of certain combinatorial structures, called sequential convexifiability, shown by Balas 1974, 1979 to hold for facial disjunctive programs. Sequential convexifiability means that the convex hull of a nonconvex set defined by a collection of constraints can be generated by imposing the constraints one by one, sequentially, and generating each time the convex hull of the resulting set. This document extends the class of problems considered to disjunctive programs with infinitely many terms, also known as reverse convex programs, and give necessary and sufficient conditions for the solution sets of such problems to be sequentially convexifiable. The authors point out important classes of problems in addition to facial disjunctive programs (for instance, reverse convex programs with equations only) for which the conditions are always satisfied. Finally, given, are examples of disjunctive programs for which the conditions are violated, and so the procedure breaks down
Statistical analysis of some traveling salesman algorithms by Egon Balas( Book )

3 editions published in 1984 in English and held by 4 WorldCat member libraries worldwide

This paper reports the results of a statistical analysis of the performance of three branch and bound algorithms for the general (asymmetric) traveling salesman problem on randomly generated test problems with up to 325 cities. Three types of functions, polynomial, superpolynomial (long-exponential) and exponential, were fitted to the performance data of each of the algorithms by least squares techniques. The three functions describe almost equally well the behavior of the algorithms in the range of problem sizes examined
Duality in discrete programming by Egon Balas( Book )

2 editions published between 1968 and 1970 in English and held by 4 WorldCat member libraries worldwide

Adjacent Vertices of the Convex Hull of Feasible 0-1 Points by Egon Balas( Book )

4 editions published in 1973 in English and held by 4 WorldCat member libraries worldwide

In the paper the authors give a constructive characterization of adjacency relations between integer vertices of the feasible set of an all zero-one program. This characterization can be used, for instance, to generate all integer vertices of the feasible set, adjacent to a given integer vertex. As a by-product, the authors establish a strong bound on the diameter of the convex hull of feasible 0-1 points. (Author)
On the Set Covering Problem by Egon Balas( Book )

3 editions published between 1970 and 1971 in English and German and held by 4 WorldCat member libraries worldwide

The paper establishes some useful properties of the equality-constrained set covering problem P and the associated linear program P'. First, the Dantzig property of transportation matrices is shown to hold for a more general class of matrices arising in connection with adjacent integer solutions to P'. Next, it is shown that for every feasible integer basis for P' there are at least as many adjacent feasible integer bases as there are nonbasic columns. Finally, given two feasible integer bases B1 and B2, it is shown that B2 can be obtained from B1 by a sequence of at most p pivots (where p is the number of columns of B2 that are not columns of B), such that each solution in the associated sequence is feasible, integer, and not worse (in terms of the objective function value) than its predecessor. (Author)
Some valid inequalities for the set partitioning problem by Egon Balas( Book )

2 editions published in 1975 in English and held by 4 WorldCat member libraries worldwide

The author introduces a family of inequalities derived from the logical implications of set partitioning constraints and investigates their properties and potential uses
A note on outer polar cuts from 0-1 points by Egon Balas( Book )

2 editions published in 1973 in English and held by 4 WorldCat member libraries worldwide

Discrete programming by the filter method with extension to mixed-integer programming and application to machine-sequencing by Egon Balas( Book )

2 editions published in 1966 in English and held by 4 WorldCat member libraries worldwide

 
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Integer programming and combinatorial optimization : 4th International IPCO Conference, Copenhagen, Denmark, May 29-31, 1995 : proceedings
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Will to freedom : a perilous journey through fascism and communism
Alternative Names
Balas Egon Amerikában élő román származású magyar zsidó matematikus, az MTA külső tagja

Egon Balas rumænsk matematiker

Egon Balas rumänischer Mathematiker

Egon Balas rumänsk matematiker

Egon Balas rumensk matematikar

Egon Balas rumensk matematiker

Egon Balas wiskundige uit Roemenië

エゴン・バラス

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