On a special monoid with a single defining relation

AbstractWe show that no finite union of congruence classes [w], w being an arbitrary element of the free monoid {a, b}∗ with unit 1, is a context-free language if the congruence is defined by the single pair (abbaab, 1). This congruence is neither confluent nor even preperfect. The monoid formed by its congruence classes is a group which has infinitely many isomorphic proper subgroups

Factorization and Resummation for Jet Broadening

Jet broadening is an event-shape variable probing the transverse momenta of particles inside jets. It has been measured precisely in e+e- annihilations and is used to extract the strong coupling constant. The factorization of the associated cross section at small values of the broadening is afflicted by a collinear anomaly. Based on an analysis of this anomaly, we present the first all-order expressions for jet-broadening distributions, which are free of large perturbative logarithms in the two-jet limit. Our formulae reproduce known results at next-to-leading logarithmic order but also extend to higher orders.Comment: 15 pages, 4 figure

Locally analytic representations and sheaves on the Bruhat-Tits building

Let L be a finite field extension of Q_p and let G be the group of L-rational points of a split connected reductive group over L. We view G as a locally L-analytic group with Lie algebra g. We define a functor from admissible locally analytic G-representations with prescribed infinitesimal character to a category of equivariant sheaves on the Bruhat-Tits building of G. For smooth representations, the corresponding sheaves are closely related to the sheaves constructed by S. Schneider and U. Stuhler. The functor is also compatible, in a certain sense, with the localization of g-modules on the flag variety by A. Beilinson and J. Bernstein.Comment: Replaces earlier version. Exposition shortened and improved in several places, and new material and examples added. In particular, section 11 is new.

Gelingendes Leben - Krise als Chance für Person & Gesellschaft. Band II

• Peter Antes, Rel.wiss. • Petra Bahr, Theol. / Journ. • Matthias Beck Med./JS, AT • Gottfried Biewer, Bildungswiss., AT • Aladin El-Mafaalani, Pol.wiss.• Johannes Eurich, Diak.wiss. • Mario Feigel, Med. CH • Heike Gramkow, Manag.Dir. • Heinrich Greving, Heilpäd. • Udo Hahn, Theol.• Maria-C. Hallwachs, Stud., Beratg. schon betroffen • Walter Hirche, Min. a.D./Präs. Dt. UNESCO • Wolfgang Jantzen †, Soz. • Jochen-C. Kaiser, Hist. • Karl-J. Kemmelmeyer, Präs. Musikrat • Hermes Kick, Med.-Ethik • Waldemar Kippes Redemptorist JN • Ferdinand Klein, SoPäd., SK • Berthold Krüger, bpb • Christian Larsen, Arzt, CH • Ulrich Lilie Präs. Diak.W • Christian Lindmeier, SoPäd., DGfE • Ralf Meister, Bischof • Bertolt Meyer, Org.- u. Wirtschaftspsych, schon betroffen, CH • Peter Neher, Präs. Caritas • Ekkehard Nuissl, Dir. Dt. Inst. EB, DIE • Ulrich Pohl, Vorst. Bethel • Hartmann Römer, Physiker • David Roth, Lt. Hospiz • Hartmut Schlegel SoPäd. • Joachim Schoss, Unternehmer, schon betroffen, CH • Walter Surböck Med., AT• Karl-H. Steinmetz, Trad. Europ. Med., AT • Rudolf Tippelt, Bildg. Forschg. • Inge Wasserberg, Inklu.Beratg. • Walter Thirring †, Phys. CERN, C

On Twist-Closed Trios

Abstract The language theoretic operation twist from JaPe 87] is studied in connection with the semiAFLs of languages accepted by reversal bounded multipushdown and multicounter acceptors. It is proved that the least twist-closed trio generated by MIR := fww rev j w 2 fa; bg g is equal to the family of languages accepted in quasirealtime by nondeterministic one-way multipushdown acceptors which operate in such a way that in every computation each pushdown makes at most one reversal. Thus, M \ (MIR) = M twist (MIR) and this family is principal both as a twist-closed and as an intersection-closed semiAFL. This is in contrast to the semiAFL of languages accepted by reversal-bounded multicounter machines in quasi-realtime. This family is a well known semiAFL which is principal as an intersection-closed semi-AFL with generator B 1 := fa n 1 a n 1 j n 2 I N g, see Grei 78], but is not principal as a semiAFL. It is here shown that it forms a hierarchy of twist-closed semiAFLs and therefore cannot be principal as twist-closed semiAFL. Zusammenfassung Die in JaPe 87] de nierte Operation twist auf W ortern und formalen Sprachen wird untersucht in Verbindung mit den semiAFL's der von umkehrbeschr ankten Keller-und Z ahlerautomaten akzeptierten Sprachen. Es wird gezeigt, da das kleinste, von der Sprache MIR := fww rev j w 2 fa; bg g generierte twist-abgeschlossene Trio identisch ist mit der Familie aller Sprachen, die von mehr-Kellerautomaten in quasi-Realzeit mit umkehrbeschr ankten Kellern akzeptiert werden. Daher ist M \ (MIR) = M twist (MIR) als durchschnitts-und als twist-abgeschlossenes Trio eine sogenannte Haupt-semiAFL (principal semiAFL). Im Unterschied dazu ist die Familie M \ (B 1 ), mit Generator B 1 := fa n 1 a n 1 j n 2 I N g, der in quasi-Realzeit von umkehrbeschr ankten mehr-Z ahlerautomaten akzeptierten Sprachen, vergl. Grei 78], zwar twist-abgeschlossen, aber es gilt nicht M \ (B 1 ) = M twist (B 1 ).

Intersecting Multisets and Applications to Multiset Languages

Abstract. We show that the family Sem = mREG = mCF of regular multiset languages is closed under applications of finite and iterated multiset-union, finite and iterated multiset-intersection, and multiset-subtraction. For the class Sem( � k) of semilinear subsets of � k, or that of � k, Sem: = � k≥0 Sem( � k), this amounts to verify, that the component-wise maximum, minimum or non-negative subtraction of pairs of elements from two semi-linear sets is again semi-linear, and that the iterated application can be replaced by a fixed finite application of multisetintersection, respectively multiset-subtraction. We solve the three questions about closure properties that remained open in [KuMi 01,KuMi 02], verify that the family mMON is not closed with respect to multiset-intersection, and correct a small mistake in a proof in [EiSc 69,Bers 79].