From: calendar@almaden.ibm.com (IBM Almaden Research Center Calendar)
Newsgroups: ba.seminars
Subject: IBM ARC seminars 31 AUG - 4 SEP 92
Date: 28 Aug 92 23:32:15 GMT


                     IBM Almaden Research Center
                           650 Harry Road
                       San Jose, CA 95120-6099

                              CALENDAR

                      August 31-September 4, 1992


08/31 - CLUSTER APPROACH TO THE CALCULATION OF ELECTRONIC STATES IN
IONIC TRANSITION METAL COMPOUNDS
W. C. Nieuwpoort, University of Groningen

Phys. Sci. Sem.    Mon., August 31    1:30 p.m.    Room:  J2-601

How ionic are ionic compounds, what do ions in solids mean?  This
conceptual question--basic to the ionic model of chemical bonding and
structure--will be considered first, in the light of the quantum
mechanical virial theorem.

The ionic model offers a good starting point for the study of (semi)
local excitations in transition metal compounds.  Ab initio cluster
calculations are in fact a necessary complement to band structure
calculations for these compounds.  These statements will be discussed
and illustrated by results of calculations on local excitation--and hold
states in NiO and La2CuO4
Host:  P. Bagus


09/01 - X-RAY RESONANT INELASTIC SCATTERING:  A NEW TECHNIQUE FOR
ELECTRONIC BANDMAPPING?
Y. Ma, University of Washington & Pacific Northwest Labs

Phys. Sci. Sem.    Tues., September 1    10:30 a.m.    Room:  D2-450

Recent high resolution synchrotron radiation excited soft x-ray emission
results on diamond, amorphous and crystalline Si will be discussed using
the formalism of inelastic scattering.  This scattering treatment
predicts that:

1.  The x-ray emission spectra are generally
    excitation-energy-dependent;

2.  Electronic momentum information can be extracted from x-ray emission
    and x-ray absorption spectra.

This will likely make it possible to map the electronic bands using only
x-ray photons.  In addition, the performance of the X1B beamline at the
NSLS will be reviewed.  Using undulator source, this SGM beamline has
achieved the highest resolution and flux in the soft x-ray region that
is comparable to the beamlines now under construction at ALS.
Host:  J. Stoehr


09/02 - FRAME SLICED PARTITIONED SIGNATURE FILES
P. Tiberio, University of Bologna, Italy

Comp. Sci. Sem.    Wed., September 2    10:00 a.m.    Room:  G2-610

The retrieval capabilities of the signature file access method have
become very attractive for many data processing applications dealing
with both formatted and unformatted data.  However, performance is still
a problem mainly when large files are used and fast response required.
In this seminar, a high performance signature file organization is
presented, integrating the latest developments both in storage structure
and parallel computing architectures.  By combining horizontal and
vertical approaches to signature file fragmentation, a new decomposition
scheme is defined, which is particularly suitable for parallel
implementation.  Performance analysis shows that this organization
provides a very good and relatively stable performance, covering the
full range of possible queries.  It outperforms any other parallel
signature file processing method which has been defined so far.  The
proposed method also offers other important advantages concerning
processing of dynamic files, adaptability to the number of available
processors, load balancing, and even fault tolerant query processing, to
some extent.

signature files.  ACM TOIS,9,4,1991.  F. Grandi, P. Tiberio, P. Zezula:
Frame-sliced partitioned parallel signature files.  ACM SIGIR'92 Conf.
Copenhagen, June 21-22, 1992.
Host:  G. Lohman


09/04 - UNDIRECTED CONNECTIVITY IN O(LOG(1.5 N) SPACE
N. Nisan, IBM Almaden Research Center

Comp. Sci. Sem.    Fri., September 4    1:30 p.m.    Room:  G2-301

We present a deterministic algorithm for the connectivity problem on
undirected graphs that runs in O(log(1.5)n) space.  Thus, the recursive
doubling technique of Savich which requires O(log2 n) space is not
optimal for this problem.

Joint work with Endre Szemeredi and Avi Wigderson.
Host:  M. Naor

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For further information on individual talks, please contact the host
listed above.

Visitors, please arrive 15 minutes early.  IBM's Almaden Research
Center (ARC) is located adjacent to Santa Teresa County Park, between
Almaden Expressway and U.S. 101, about 10 miles south of Interstate
280.  From U.S. 101, exit at Bernal Road, and follow Bernal Road west
past Santa Teresa Blvd. into the hills (ignoring the left turn for
Santa Teresa Park).  Alternatively, follow Almaden Expressway to its
southern terminus, turn left onto Harry Road, then go right at the ARC
entrance (about a quarter of a mile later) and go up the hill.  For
more detailed directions, please phone the ARC receptionist at (408)
927-1080.

IBM Almaden Research Center electronically distributes both its
complete calendar of seminars and a subset of Computer Science
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