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1/5/1
    828495  82j#34038
  Entrainment domains.
  Proceedings   of   the   VIIIth  International  Conference  on  Nonlinear
Oscillations, Vol. I (Prague, 1978)
  Meyer, K. R.; Schmidt, D. S.
  Publ: Academia, Prague
  1979,   pp. 479 - 482,
  Document Type: Collection
  Authors'  summary:  ''We develop effective algorithms for  computing  the
domains  in a parameter space where a differential equation which admits an
invariant torus has a periodic solution with fixed  rotation  number.   The
algorithms  are  based  on  the  method  of  Lie  transforms  and have been
implemented on a computer.  The algorithms are applied to two variations of
van der Pol's equation.''
  (For the entire collection see MR 82k:70002a.)
  Reviewer: Authors' summary
  Descriptors:    *ORDINARY   DIFFERENTIAL  EQUATIONS  -Qualitative  theory
--Periodic solutions (34C25)

1/5/2
    827401  82j#00001
  Turtle geometry.
  Abelson, Harold; diSessa, Andrea A.
  Publ: MIT Press, Cambridge, Mass.-London
  1981,   xx+477 pp.   0-262-01063-1
  Price: $20.00.
  Document Type: Book
  The  computer as a medium for exploring mathematics.  MIT Press Series in
Artificial Intelligence.
  This book contains a computational introduction to geometry and  advanced
mathematics at the undergraduate level. Its conception is based on the idea
that  approaching mathematics by computation --  especially by the activity
of programming --  and by doing it is more  effective  than  only  learning
about  it.   Because  of  the  emergence  of  powerful inexpensive personal
computers the student today gets the chance to  experience  mathematics  in
terms  of  constructive process-oriented formulations instead of axiomatic-
deductive formalisms.
  The first turtles designed at the Massachusetts Institute  of  Technology
where  this  material  was created during the past ten years were computer-
controlled robots that moved around the floor in response to the  commands,
''FORWARD''  and ''RIGHT''.  The turtle that brings ''Turtle geometry''  to
life is a glowing tracer moving on the display screen of a  small  computer
system. Chapter 1 shows how to regard plane geometric figures not as static
entities  but  as  tracings  of this turtle controlled by suitable computer
programs leading to such concepts as rotation number of closed paths  in  a
natural  way.   Chapter  2  demonstrates procedures for random and directed
motion and for simulating growth processes in mathematical biology. Chapter
3 compares turtle methods and coordinate methods for representation of two-
or three- dimensional geometric objects on the screen.  Chapter 4 discusses
the  topology  of curves in the plane.  In Chapter 5 the turtle escapes the
plane and begins to move on nonflat surfaces (Chapters 6, 7, 8). In Chapter
9 this computational exploration of curved surfaces provides a conceptional
framework for studying Einstein's general theory of relativity.
  Although most parts of the book  are  accessible  with  only  pencil  and
paper,   the  contents  will  be  most  useful  to those who have access to
interactive computer graphics.   Many  of  the  sections  contain  extended
descriptions of computer projects to implement and investigate.
  An  appendix  includes  a  typical  implementation  of turtle commands in
BASIC,  which can be used for most computer graphic systems.  In  addition,
there  are  listed  a few commercially available computer systems that have
turtle graphics built in.
  Reviewer: KAHMANN, J.
  Descriptors: *GENERAL --General mathematics (00A05); GEOMETRY  --Explicit
machine computation and programs   (51-04);   COMPUTER  SCIENCE  (including
AUTOMATA)   -Simulation  --None of the above,  but in this section (68J99);
RELATIVITY --Explicit machine computation and programs   (83-04);   BIOLOGY
AND   BEHAVIORAL  SCIENCES  --Explicit  machine  computation  and  programs
(92-04)

1/5/3
    825895  82i#58061
  Rotation sets are closed.
  Ito, Ryuichi
  Math. Proc. Cambridge Philos. Soc.,   1981,   89, no. 1,   107 - 111.
  Document Type: Journal
  The  rotation  number  of  an orientation-preserving homeomorphism of the
circle S=R/Z measures the average rotation of the orbit of each point under
iterations of the homeomorphisms.  S.  Newhouse,  J.  Palis and F.   Takens
(''Bifurcations  and  stability  of  families  of diffeomorphisms'',  Inst.
Hautes Etudes Sci.  Publ.  Math.,  to appear)  generalized this concept  to
include  maps of S (continuous endomorphisms of S which are not necessarily
injective) of degree one. In particular, given such a map f: S{arrr}S and a
lift F of f to the covering space R,  the rotation number  is  defined  for
each  x{in}R  to  be  rho  (F,  x)=lim sup{sub}(n{arrr}{infin})  n{sup}(  -
1)(F{sup}n(x) - x). When f is a homeomorphism, rho (F, x) is independent of
x. Hence, the appropriate generalization of the rotation number for maps is
the rotation set rho (F)= (rho (F, x): x{in}R). Newhouse,  Palis and Takens
proved that the closure of rho (F)  is either a point or a closed interval.
In the present article this result is strengthened;  the author proves that
rho (F) is closed.
  Reviewer: CHICONE, CARMEN (Columbia, Mo.)
  Descriptors:    *GLOBAL   ANALYSIS,   ANALYSIS  ON  MANIFOLDS   -Ordinary
differential equations on manifolds;   dynamical  systems   --None  of  the
above,    but   in   this   section   (58F99);    MEASURE  AND  INTEGRATION
-Measure-theoretic ergodc theory  --None of the above, but in this section
(28D99)

1/5/4
    817982  82g#05053
  On rotation numbers for complete bipartite graphs.
  Cockayne, E. J.; Lorimer, P. J.
  Congr. Numer.,   1980,   28, ,   281 - 291.
  Document Type: Journal
  Proceedings  of  the  Eleventh  Southeastern Conference on Combinatorics,
Graph Theory and Computing (Florida Atlantic  Univ.,   Boca  Raton,   Fla.,
1980), Vol. I.
  The rotation number h(G,  x)  of a graph G having one vertex x designated
as its root is the minimum integer m for  which  there  exists  a  graph  F
having the same number of vertices as G and having m edges, such that,  for
any vertex y of F,  there exists an embedding f  of  G  into  F  for  which
f(x)=y. F is an extremal (G, x)  graph if its number of edges realizes this
minimum.  Section  2  is  concerned  with  rotation  numbers  for  complete
bipartite graphs.
  For  each integer 2{sup}k the authors define a rooted tree (T{sub}k,  u).
''Broadcasting''  in time k is possible from any source y in a graph G on 2
{sup}k  vertices if and only if there exists an embedding f of T{sub}k into
G such that f(x)=y.  (''By broadcasting,  we mean information dissemination
in  communications networks whereby a single message known initially to one
member (the source)  becomes known to all members.   The  dissemination  is
accomplished  by  a  series  of  phone calls over the edges of the network,
subject to the following constraints: (i) Each phone call requires one unit
of time; (ii) a vertex may participate in only one call per unit time;  and
(iii) a vertex may only call an adjacent vertex.'')
  Reviewer: BROWN, W. G. (Montreal, Que.)
  Descriptors:  *COMBINATORICS  -Graph theory  --Extremal problems (05C35);
COMBINATORICS  -Graph theory  --Trees (05C05)

1/5/5
    815323  82f#34051
  Systems  of  differential equations with switching that are periodic with
respect to two arguments.
  Ivanov, A. F.
  Visnik Kiiv. UnivMat. Meh.,   1978,   , No. 20,   28 - 32, 164.
  Languages: Ukrainian   Summary Languages: English and Russian summaries
  Document Type: Journal
  The author considers the system of differential equations d theta /d  phi
=f{sub}i(phi , theta ) (i=1, 2, ... ,k) with switchings on the line q theta
=p phi , where the functions f{sub}i are 2 pi -periodic with respect to the
scalar variables phi , theta , and p, q are integers. He proves that in the
absence of a sliding regime every solution has a rotation number,  and that
a solution is periodic precisely when its rotation number is rational.
  Reviewer: ZADOROZNII, V. G. (Voronezh)
  Descriptors:   *ORDINARY  DIFFERENTIAL  EQUATIONS   -Qualitative   theory
--Dynamical systems  (34C35)

1/5/6
    797483  81m#85003
  Orbits near a 2/3 resonance.
  Michaelidis, P.
  Astronom. and Astrophys.,   1980,   91, no. 1-2,   165 - 174.
  Document Type: Journal
  In  this  paper  the  author  has  studied  the orbits in a galactic type
potential V={1/2}(Ax{sup}2+By{sup}2)   -   epsilon  xy{sup}2  in  the  near
resonance  case {root}(A/B){simeq}(2/3).  A large number of periodic orbits
have been found empirically and by means of the third integral.  The orbits
are determined by using the Lie transforms, or by a computer programme that
gives  the ''third integral''  up to 14th degree.  Resonant periodic orbits
appear for epsilon  > 1.65.
  Some nonperiodic orbits have also been calculated in order  to  find  the
rotation  number  as  a  function of the distance from the central periodic
orbit.
  The theoretical results so obtained have been compared with the empirical
results regarding (i)  the position of periodic orbits,  (ii)  the shape of
different  characteristics and (iii)  the values of rotation number.  It is
found that there is agreement between empirical and theoretical values  for
0 <= epsilon  <= 2.1. If epsilon  > 2.1 the positions of periodic orbits do
not agree with those found empirically.
  Reviewer: BHATNAGAR, K. B. (Delhi)
  Descriptors:    *ASTRONOMY  AND  ASTROPHYSICS    --Galactic  and  stellar
dynamics (85A05);   GLOBAL  ANALYSIS,   ANALYSIS  ON  MANIFOLDS   -Ordinary
differential   equations   on  manifolds;   dynamical  systems   --Periodic
solutions (58F22);  MECHANICS OF PARTICLES  AND  SYSTEMS   -Dynamics  of  a
system  of  particles,  including celestial mechanics --Celestial mechanics
(70F15)

1/5/7
    796331  81m#58049
  Centralisateur  d'un diffeomorphisme du cercle dont le nombre de rotation
est irrationnel.
  Yoccoz, Jean-Christophe
  C. R. Acad. Sci. Paris Ser. A-B,   1980,   291, no. 9,   A523 - A526.
  Languages: French   Summary Languages: English summary
  Document Type: Journal
  Author's summary:  ''Let f be a  C{sup}{infin}  orientation-   preserving
diffeomorphism   with   irrational  rotation  number  alpha  ,   (p{sub}n/q
{sub}n){sub}(n{in}N)  the convergents of alpha .   Using  a  theorem  which
estimates    f{sup}(q{sub}n{sub}+{sub}1)     from   f{sup}(q{sub}n)    when
q{sub}(n+1)/q {sub}n is big,   we  obtain  properties  of  centralizers  in
Diff{sub}+{sup}   {infin}(T{sup}1);    for   example,    we   construct   a
diffeomorphism with irrational rotation number and discrete centralizer  in
Diff{sub}+{sup}{infin}(T{sup}1).''
  Reviewer: Author's summary
  Descriptors:    *GLOBAL   ANALYSIS,   ANALYSIS  ON  MANIFOLDS   -Ordinary
differential equations on manifolds;  dynamical systems  --Ergodic  theory;
invariant  measures   (58F11);  MEASURE AND INTEGRATION  -Measure-theoretic
ergodic theory  --None of the above, but in this section (28D99)

1/5/8
    789772  81j#58055
  Chaotic behavior in piecewise continuous difference equations.
  Keener, James P.
  Trans. Amer. Math. Soc.,   1980,   261, no. 2,   589 - 604.
  Document Type: Journal
  A  class of difference equations:  x{sub}(k+1)=F(x{sub}k),  where F:  (0,
1){arrr}(0, 1) is piecewise continuous, is investigated.  The following are
assumed: (i)  F is piecewise continuously differentiable with a single jump
discontinuity at some theta {in}(0, 1); (ii)  for x{neq} theta ,  0 <  t <=
dF/dx  <=   s  <   {infin};   (iii)   F(x){arrr}0  as x{arrr} theta {sup}+,
F(x){arrr}1 as x{arrr} theta {sup} - , and F(theta ) equals 0 or 1.
  For x{in}(0,  1)  the rotation number is defined  (roughly)   to  be  the
fraction  of  the iterates of x under F contained within (theta ,  1).  The
difference equation is considered  to  be  chaotic  if  the  range  of  the
rotation numbers rho (x) contains a nontrivial interval. Results are proven
for two cases: For F(0) > F(1): rho (x) is constant;  if F depends smoothly
on some lambda , then rho (x, lambda )  is rational except for a Cantor set
in  lambda  ;  when rho  is rational all solutions are eventually periodic,
and when rho is irrational {hat}{sub}(k=0){sup}{infin} F{sup}((k))((0,  1))
is a Cantor set. For F(0) < F(1):  rho (x)  covers a ntrivial interval if
F(1)  -  F(0)  is sufficiently large;  if dF/dx >=  t >  1 then rho (x)  is
nowhere continuous;  if t <  1 then rho (x)  may be constant on an interval
having other values on at most a Cantor set.
  Reviewer: MAROTTO,FREDERICK R. (New York)
  Descriptors:   *GLOBAL  ANALYSIS,   ANALYSIS  ON   MANIFOLDS    -Ordinary
differential   equations   on   manifolds;   dynamical  systems   --Strange
attractrs;  chaos and other pathologies (58F13);  FINITE  DIFFERENCES  AND
FUNCTIONAL EQUATIONS -Finite differences  --Difference equations (39A10)

1/5/9
    786512  81i#58035
  Nonconjugacy  of  a  minimal  distal  diffeomorphism  of the torus to a C
{sup}1 skew-product.
  Rees, M.   (Rees, Mary)
  Israel J. Math.,   1979,   32, no. 2-3,   193 - 200.
  Document Type: Journal
  Let T{sub}f(x,  y)=(f(x),  x+y)  be a minimal distal homeomorphism of the
torus,   where f is a minimal homeomorphism of the circle.  Then T{sub}f is
topologically conjugate to the skew product S{sub}(alpha , phi )(x, y)= (x+
alpha , y+ phi (x)), where alpha  is the rotation number of f and phi  is a
homeomorphism conjugating f and rotation by alpha .  A.  Finzi (Ann.   Sci.
Ecole Norm. Sup. (3) 67 (1950), 243 - 305; MR 12, 434)  has shown that if f
is C{sup}3 and alpha  lies outside some exceptional set,  then the (in this
case unique)  conjugating homeomorphism phi ,  and hence the skew product S
{sub}(alpha , phi ), must be C{sup}1.
  The author shows by example that even if f is C{sup}{infin}, T{sub}f need
not be topologically conjugate to any  C{sup}1  skew  product  S{sub}(alpha
,g), where g is a C{sup}1 map of the circle to itself.  The construction is
similar to V. I. Arnol'd's construction (Izv. Akad. Nauk SSSR Ser. Mat.  25
(1961), 21 - 86; MR 25#4113; translated in Amer. Math. Soc. Transl. (2)  46
(1965), 213 - 284; see MR  32 #1081) of a minimal analytic homeomorphism of
the circle such that the unique homeomorphism conjugating it and a rotation
is not absolutely continuous.
  Reviewer: COVEN, ETHAN M. (Middletown, Conn.)
  Descriptors:   *GLOBAL  ANALYSIS,   ANALYSIS  ON   MANIFOLDS    -Ordinary
differential  equations  on  manifolds;   dynamical  systems  --None of the
above,   but  in   this   section   (58F99);    MEASURE   AND   INTEGRATION
-Measure-theoretic ergodic theory  --None of the above, but in this section
(28D99)

1/5/10
    786506  81i#58029
  Topological  invariants of germs of analytic mappings and area preserving
mappings,  and their application  to  analytic  differential  equations  in
CP{sup}2.
  Naishul', V. A.
  Funkcional. Anal. i Prilozhen.,   1980,   14, no. 1,   73 - 74.
  Languages: Russian
  Document Type: Journal
  The  author  considers two classes of mappings (C,  0){arrr}(C,  0),  the
class A of analytic mappings and the class G of mappings differentiable  at
the  point zero and preserving two-dimensional Lebesgue measure.  A mapping
from A or G is called a nonlinear rotation by an angle phi {in}R (mod 2  pi
)   if  its  linear  part  is a rotation by phi .  A lifting of a nonlinear
rotation to the universal covering  of  a  punctured  neighborhood  of  the
origin  is called a covering rotation;  the number phi /2 pi  is called the
rotation number of the covering rotation.  The author proves the  following
results  for  mappings  from the classes A and G:  (1)  If two mappings are
topologically equivalent and one of them is a nonlinear rotation (about  an
angle phi {neq}0, pi  (mod 2 pi ) in the case of G), then the second one is
a  nonlinear  rotation.   (2)  The linear part of a nonlinear rotation is a
topological invariant. (3)  The rotation number of a covering rotation is a
topological invariant. It is shown that the assertions (2) and (3)  are not
true for infinitely differentiable and  real  analytic  mappings  (R{sup}2,
0){arrr}(R{sup}2,   0).   An  application to the classification of analytic
differential equations in CP {sup}2 is given.
  (English translation: Functional Anal. Appl. 14 (1980), no. 1, 59 - 60.)
  Reviewer: GLIKLIH, JU. E. (Voronezh)
  Descriptors:   *GLOBAL  ANALYSIS,   ANALYSIS  ON   MANIFOLDS    -Ordinary
differential equations on manifolds;  dynamical systems  --Stability theory
(58F10);  REAL FUNCTIONS  -Miscellaneous topics  --Real-analytic  functions
(26E05);   ORDINARY  DIFFERENTIAL  EQUATIONS -General theory --Differential
equations i the complex domain  (34A20)

1/5/11
    785552  81i#28023
  The action of diffeomorphism of the circle on the Lebesgue measure.
  Katznelson, Y.
  J. Analyse Math.,   1979,   36, ,   156 - 166 (1980).
  Document Type: Journal
  Any diffeomorphism of the circle is a nonsingular isomorphism relative to
Lebesgue  measure  mu  .   Suppose  that  f  is  an  orientation-preserving
diffeomorphism of the circle whose rotation number rho (f)   has  unbounded
continued fraction coefficients.  It is shown that if f is C{sup}2 then the
nonsingular system (f,  mu )  is orbit equivalent to  an  odometer  (adding
machine)   of  product  type.   (Every ergodic nonsingular isomorphism of a
Lebesgue space is orbit equivalent to some odometer, but not necessarily to
one of product type.)  The following converse is also proved.  For a  given
odometer  theta  of product type,  the set of orientation-preserving C{sup}
{infin} diffeomorphisms of the circle which are orbit equivalent  to  theta
is    C{sup}{infin}    dense    in    the    set   of   all   C{sup}{infin}
orientation-preserving diffeomorphisms with irrational rotation numbers.
  Reviewer: WALTERS, PETER (Coventry)
  Descriptors:  *MEASURE AND INTEGRATION  -Measure-theoretic ergodic theory
--None of the above, but in this section (28D99); GLOBAL ANALYSIS, ANALYSIS
ON  MANIFOLDS   -Ordinary  differential  equations on manifolds;  dynamical
systems  --Ergodic theory; invariant measures  (58F11)

1/5/12
    783273  81h#58039
  Sur  la  conjugaison  differentiable des diffeomorphismes du cercle a des
rotations.
  Herman, Michael-Robert
  Inst. Hautes Etudes Sci. Publ. Math.,   1979,   , No. 49,   5 - 233.
  Languages: French
  Document Type: Journal
  If f is a diffeomorphism of the circle, isotopic to the identity,  with a
lift f to the real line, the rotation number rho (f) is defined to be alpha
=   rho (f)=lim{sub}(n{arrr}{infin})  f{sup}n(x)/n (which is independent of
x). V. I. Arnol'd proved in 1961 (Izv. Akad. Nauk SSSR Ser. Mat. 25 (1961),
21 - 86; MR 25#4113; translated in Amer. Math. Soc. Transl. (2)  46 (1965),
213 -  284; MR 32#1081) that if f is a C{sup} omega -diffeomorphism and rho
(f)=   alpha  satisfies a certain Diophantine condition,  then f is C {sup}
omega -conjugate to a rotation.  He further conjectured that there exists a
set  A{lhk}(0,   1){sbs}Q  of  measure  1  such that if f is a C{sup} omega
-diffeomorphism and alpha {in}A then f is C{sup} omega -conjugate to R{sub}
alpha , the rotation through an angle 2 pi alpha .
  The principal result of this paper is a proof of a  stronger  version  of
the conjecture. If f is a C{sup}r-diffeomorphism, 3 <= r <=  omega  and rho
(f)=  alpha  satisfies a certain condition (which determines a set of  full
Lebesgue measure) then f is C{sup}(r - 1- beta )-conjugate to R{sub} alpha
for all beta  > 0, beta {in}R (beta  is a Holder condition on the (r - 1)st
derivative of f).
  The paper is, however, much more than just a proof of this result;  it is
a complete,  detailed study of diffeomorphisms of the circle.  It  contains
many new results, now well known due to expository articles by H. Rosenberg
and P.  Deligne (for a more complete review,  the reader is referred to the
review of the last-mentioned papers (Rosenberg,  Seminaire Bourbaki,   Vol.
1975/76, 28eme annee, Exp. No. 476, pp.  81 -  98,  Lecture Notes in Math.,
Vol. 567, Springer, Berlin, 1977; MR 56 #13291a; Deligne, ibid.,  Exp.  No.
477,   pp.  99 -  121;  MR 56 #13291b)).  The present paper also contains a
complete discussion of the classical results concerning diffeomorphisms  of
the  circle  together with new proofs,  examples and insightful analyses of
the consequences which result from the author's unique point of view.   The
last   chapter  gives  examples  and  generalizations  on  T{sup}n  and  an
independent appendix discusses and gives a new proof for Arnol'd's  theorem
on small divisors.
  Reviewer: HARTZMAN, C. S. (Halifax, N.S.)
  Descriptors:    *GLOBAL   ANALYSIS,   ANALYSIS  ON  MANIFOLDS   -Ordinary
differential equations on manifolds;  dynamical systems  --Ergodic  theory;
invariant  measures   (58F11);  MEASURE AND INTEGRATION  -Measure-theoretic
ergodic theory  --None of the above, but in this section (28D99)

1/5/13
    780029  81g#58030b
  Periodic  and conditionally periodic trajectories in conservative systems
under minimal conditions of smoothness. II.
  Antonov, V. A.
  Leningrad. Gos. Univ. Uchen. Zap.,   1979,   ,  No.  400 Ser.  Mat.  Nauk
Vyp. 57 Trudy Astronom. Obser. 35,   127 - 142, 220.
  Languages: Russian   Summary Languages: English summary
  Document Type: Journal
  The   author  considers  periodic  trajectories  (cycles)   of  an  area-
preserving homeomorphism P of a plane circular annulus.  Various  dynamical
problems (orbits of stars in stellar accumulations and others) lead to such
mappings (nonsmooth or mappings of small order of smoothness).  The mapping
P shifts all radii into one side and  satisfies  the  ''radii  distortion''
condition  (roughly speaking,  a point with a larger radius is shifted by a
larger angle).  Let q be the number of points in a cycle,  p the number  of
complete  revolutions of a cycle,  nu =p/q the rotation number.  The author
studies the so-called regular cycles:  nu =p/q is an irreducible  fraction,
and  the  azimuths  theta {sub}i of points in a cycle satisfy the condition
((theta {sub}j - theta {sub}i)/2 pi )=((j - i) nu ). The main result of the
first paper is the following:  For every rational  nu   lying  between  the
rotation  numbers  of  the interior and the exterior circles there exists a
regular cycle with the rotation number nu .  For q=1 this result was proved
by  Poincare  (a  fixed point is a regular cycle).  In the second paper the
author studies ''minimal''  (in the sense of  the  variational  definition)
regular cycles and ''alternating'' regular cycles lying between ''minimal''
cycles  (all  cycles  for  a  fixed nu ).  He shows that there is always an
alternating cyclelying between two minimal cycles.  In the known  examples
the minimal and alternating cycles correspond to stable and unstable closed
trajectories. The articles are notable for their detailed exposition.
  Reviewer: GLIKLIH, JU. E. (Voronezh)
  Descriptors:    *GLOBAL   ANALYSIS,   ANALYSIS  ON  MANIFOLDS   -Ordinary
differential  equations  on  manifolds;   dynamical   systems    --Periodic
solutions  (58F22);   MECHANICS OF PARTICLES AND SYSTEMS  -Linear vibration
theory  --Conservative  systems  (70J15);    ASTRONOMY   AND   ASTROPHYSICS
--Galactic and stellar dynamics (85A05)

1/5/14
    764883  81b#34028
  Computer studies of nonlinear oscillators.
  Nonlinear oscillations in biology (Proc. Tenth Summer Sem.  Appl.  Math.,
Univ. Utah, Salt Lake City, Utah, 1978)
  Hoppensteadt, Frank C.
  Publ: Amer. Math. Soc., Providence, R.I.
  1979,   pp. 131 - 139, Lectures in Appl. Math., 17,
  Document Type: Collection
  A sample of nonlinear oscillation problems  is  presented  to  illustrate
several numerical methods which have been successfully applied to the study
of  oscillanomena.  Results are summarized in this survey article.
First, studies of Mathieu's equation suggest computer experiments which can
be performed to study the response of a  pendulum  to  oscillation  of  its
support point. A pendulum having a vertically oscillating support point can
have  three  (at least)  stable responses coexisting for the same parameter
values of forcing and tuning;  the straight up and straight down  positions
as  well  as a continual rotation are all stable solutions of this problem.
Computer experiments can be used in these cases to determine the domains of
attraction of the various modes of response. This example also demonstrates
the  interesting  fact  that  otherwise  unstable  static  states  can   be
stabilized by external oscillatory forcing.
  Next,  stable  oscillatory  responses  of  the  van  der Pol equation to
periodic forcing are described.  The concept of rotation number can be used
to  summarize  numerical  experiments on subharmonic solutions.  Then it is
described how computation of the power spectrum can be used  to  study  the
presence of higher harmonics.
  Finally,   computer  studies  of  certain  chaotic  dynamical systems are
discussed.  Numerical simulations are used to  describe  density  functions
characterizing random behavior of deterministic oscillators.
  (For the entire collection see MR 81a:92002.)
  Reviewer: AMES, W. F. (Atlanta, Ga.)
  Descriptors:    *ORDINARY   DIFFERENTIAL  EQUATIONS  -Qualitative  theory
--Nonlinear oscillations (34C15);  GLOBAL ANALYSIS,  ANALYSIS ON  MANIFOLDS
-Ordinary differential equations on manifolds; dynamical systems  --Strange
attractors; chaos and other pathologies (58F13)

1/5/15
    757303  80k#58080
  Sur la structure des bifurcations des diffeomorphismes du cercle.
  Mira, Christian
  C. R. Acad. Sci. Paris Ser. A-B,   1978,   287, no. 13,   A883 - A886.
  Languages: French   Summary Languages: English summary
  Document Type: Journal
  Piecewise linear mappings of the form x 3a+ lambda {sub}1x for x < 0, and
x 3 - b+ lambda {sub}2x for x > 0 with a, 3b > 0,  x{in}R have been studied
by many authors,  including N.  N.  Leonov (Izv.  Vyssh.   Uchebn.   Zaved.
Radiofizika 2 (1959), no. 6, 942 - 956).  In the present paper,  the author
adapts Leonov's results to mappings of the circle having the form theta   3
theta + lambda +g(theta ); lambda {in}( -  2 pi ,  30),  theta {in}S{sup}1,
where g(theta )= g(theta +2 pi ) and g(0){neq}0, g'(0)=0,  {vert}g'(theta )
{vert} < 1. It is shown that period-doubling bifurcations occur in infinite
sequences associatd with which one has a ''box within box'' structure. The
behavior of the rotation number mu =  mu (lambda )  as the parameter lambda
varies is also discussed,  it being shown that there is  a  Cantor  set  of
lambda  values for which mu  is irrational.
  Reviewer: HOLMES, P. J. (Ithaca, N.Y.)
  Descriptors:    *GLOBAL   ANALYSIS,   ANALYSIS  ON  MANIFOLDS   -Ordinary
differential equations  on  manifolds;   dynamical  systems   --Bifurcation
theory and singularities (58F14)

1/5/16
    722330  58#31279
  Conjugaison  C{sup}{infin}  des  diffeomorphismes  du cercle pour presque
tout nombre de rotation.
  Herman, Michael-Robert
  C. R. Acad. Sci. Paris. Ser. A-B,   1976,   283,  no.  8,    Aii,  A579 -
A582.
  Languages: French   Summary Languages: English summary
  Document Type: Journal
  Author's  summary:   ''We  announce  that Theorem 1 of our preceding note
(same C. R. Ser. A-B 282 (1976), no. 10, A503 - A506;  MR 55#6448)  is true
for  a  set   A of numbers of T{sup}1 of Haar measure equal to 1 (A is also
meager in T{sup}1):  If f is a diffeomorphism of S{sup}1  of  class  C{sup}
{infin}, of rotation number alpha {in}A,  then f is C{sup}{infin}-conjugate
to the rotation R{sub} alpha  of rotation number alpha .   This  settles  a
conjecture of V. I. Arnol'd. ''
  A  detailed  version  of  the  author's work has recently appeared (Inst.
Hautes Etudes Sci. Publ., No. 49, (1979), 5 - 235).
  Reviewer: Editors
  Descriptors:   *GLOBAL  ANALYSIS,   ANALYSIS  ON  MANIFOLDS    -Ordinary
differential  equations  on  manifolds;   dynamical  systems  --None of the
above,  but in this section (58F99);  MEASURE AND  INTEGRATION   -Classical
measure  theory  --Measure-preserving  transformations,   flows  (dynamical
systems), measure-theoretic ergodic theory  (28A65)

1/5/17
    722257  58#31210
  Differentiable  dynamics.   An  introduction  to  the  orbit structure of
diffeomorphisms.
  Nitecki, Zbigniew
  Publ: The M.I.T. Press, Cambridge, Mass.-London
  1971,   xv+282 pp.
  Price: $6.50.
  Document Type: Book
  The book is a revised version of lecture notes for a course given by  the
author at Yale in 1969.  It is based on ideas presented by S.  Smale in his
1967 survey article (Bull.  Amer.  Math.  Soc.  73 (1967),  747 -  817;  MR
37#3598;   erratum,  MR  39,  p.  1593)  and subsequently developed by many
authors.  Crudely speaking,  the Smale program has two objectives:  (1)  to
find generic properties of dynamical systems,  i.e.,  properties which hold
for ''almost all''  systems;  and (2)  to prove that  certain  systems  are
''stable'',   i.e.,   have qualitative behavior which is unchanged by small
perturbations of the system.   The  author  explains  the  program,   gives
detailed examples and proves many of the basic theorems.
  Here  is  a list of the chapter titles together with an indication of the
contents:  (1)  The circle:  rotation number,  Denjoy's example,  Peixoto's
generic theory;  (2)  Periodic points:  local behavior (Hartman's theorem),
stable manifold  theory,   Kupka-Smale  genericity  theorem;   (3)   Anosov
diffeomorphisms:   examples  and stability theorem;  (4)  The horseshoe:  a
detailed construction and its relation to Bernoulli shifts; (5)  Hyperbolic
sets:  stable manifold theory,  local product structure,  proof that for an
Axiom A system every point is asymptotic to a nonwandering point;  (6)  The
Omega -stability theorem:  a detailed proof;  (7)  Survey of recent (at the
time of writing) work.
  Reviewer: J. W. Robbin (Madison, Wis.)
  Descriptors:   *GLOBAL  ANALYSIS,   ANALYSIS  ON   MANIFOLDS    -Ordinary
differential equations on manifolds;  dynamical systems  (58Fxx);  ORDINARY
DIFFERENTIAL EQUATIONS-Qualitative theory --Dynamical systems  (34C35)

1/5/18
    707397  58#17324
  Frequency entrainment of a forced van der Pol oscillator.
  Flaherty, J. E.; Hoppensteadt, F. C.
  Studies in Appl. Math.,   1978,   58, no. 1,   5 - 15.
  Document Type: Journal
  This  is  an  interesting  study  of  a van der Pol relaxation oscillator
subject to external sinusoidal forcing:
     (d{sup}2u/dt{sup}2)+k(u{sup}2 - 1)(du/dt)+u= mu kB cos(mu t+ alpha ).
  The model is studied for the parameters satisfying alpha =0, mu =1, 0 < B
< 0.8, 0 < 1/k < 0.2. The numerical computing of the rotation number (rho )
suggests that it defines a continuous but piecewise constant surface except
in overlap regions where it is double-valued, having what looks like folds.
The parameter ranges where rho  is single-valued illustrate the  phenomenon
of  locking  phase,   the  successive bifurcation of stable subharmonic and
almost periodic oscillations.  The paper gives an indication of the  nature
of  stable  responses  of  this  system,   which  poses  difficult analytic
problems.
  Reviewer: G. V. Hmelevskaja-Plotnikov (Jambes)
  Descriptors:   *ORDINARY  DIFFERENTIAL  EQUATIONS   -Qualitative   theory
--Nonlinear  oscillations  (34C15);   MECHANICS  OF  PARTICLES  AND SYSTEMS
--Ordinary differential equations (70.34)

1/5/19
    611858  53#6012
  The  stability  of  the rotation number of a doubly periodic differential
equation.
  Ershov, E. K.
  Differencial'nye Uravnenija,   1975,   11, no. 11,   1949 - 1955, 2107.
  Languages: Russian
  Document Type: JOURNAL
  Reviewer: Ju. G. Borisovich
  Descriptors:   *ORDINARY  DIFFERENTIAL  EQUATIONS   -Qualitative   theory
--Periodic solutions (34C25)

1/5/20
    597333  52#8566
  Dependence  on  a  parameter  of  the  rotation  number of a differential
equation defined on the torus.
  Ershov, E. K.
  Differencial'nye Uravnenija,   1975,   11, no. 10,   1774 - 1779, 1907.
  Languages: Russian
  Document Type: JOURNAL
  Reviewer: L. Reizinsh
  Descriptors:   *ORDINARY  DIFFERENTIAL  EQUATIONS   -Qualitative   theory
--Periodic  solutions  (34c25);   GLOBAL  ANALYSIS,   ANALYSIS ON MANIFOLDS
-Ordinary  differential  equations   on   manifolds;    dynamical   systems
--Periodic points and zeta functions (58f20)

1/5/21
    556329  49#11567
  Generic    properties   of   the   rotation   number   of   one-parameter
diffeomorphisms of the circle.
  Brunovsky, Pavol
  Czechoslovak Math. J.,   1974,   24(99), ,   74 - 90.
  Document Type: JOURNAL
  Reviewer: L. Reizinsh
  Descriptors:   *GLOBAL  ANALYSIS,   ANALYSIS  ON   MANIFOLDS    -Ordinary
differential  equations on manifolds;  dynamical systems  --Periodic points
and zeta functions (58f20)

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   $15.79  0.287 Hrs File239 4 Descriptors



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