BULLETIN OF THE
AMERICAN MATHEMATICAL SOCIETY
Volume 81, Number 1, January 1975
JOSEPH L. WALSH
IN MEMORIAM
BY MORRIS MARDEN
Threescore years and ten is the biblical measure of a man's normal
life span. Yet in modern times his surpassing of this bound is not unusual.
However, it becomes noteworthy when he is blessed with undiminished
physical and mental vigor. This was true of Joe Walsh. "His spirit was
marvelous until the end, and he spoke with gratitude for his many pro-
ductive years."1
Joseph Leonard Walsh died on December 10, 1973 at the age of seventy
eight years in his home at University Park, Maryland. This site is not far
from where he was born on September 21, 1895, as son of Reverend and
Mrs. John Leonard Walsh. Most of his academic life as student, teacher
and scholar was spent at Harvard University. In 1916 Harvard awarded
him the S.B. degree, summa cum laude, and at the same time a Sheldon
Traveling Fellowship for study at the Universities of Chicago and Wis-
consin. On his return to Harvard in 1917, Walsh began some studies
under Maxime Bôcher, but their progress was interrupted by World War I
and his enlistment as an ensign in the U.S. Navy. In 1920 Harvard granted
him a Ph.D. and also a second Sheldon Traveling Fellowship, this time
for study in Paris under Paul Montel. Back from Europe in 1921 he joined
the Harvard faculty, but in 1925 took a leave-of-absence for a year's
research at Munich under Carathéodory. Returning again to Harvard,
he was promoted through the ranks to a full professorship in 1935 and
served as department chairman from 1937 to 1942. In the latter year he
was recalled to active duty in the U.S. Navy as a lieutenant commander.
When he returned to Harvard in 1946, he was appointed to the pres-
tigous Perkins Professorship, which he held until his retirement in 1966.
A semester earlier he began a research professorship at the University of
Maryland, in which position he remained fully active, working with Ph.D.
and post doctoral students, until a few months before his death.
During Walsh's lifetime he received many academic and nonacademic
honors. Among them was his election in 1936 to the National Academy
of Science, and in 1937 to the vice-presidency of the American Mathemati-
cal Society. He was elected for a two-year term as president of the Society
in 1949. This was a crucial period for the Society when it was experiencing
1 Letter from Mrs. Joseph L. Walsh.
Copyright © American Mathematical Society 1975
45
License or copyright restrictions may apply to redistribution; see https://www.ams.org/journal-terms-of-use
46 MORRIS MARDEN [January
JOSEPH L. WALSH (1895-1973)
License or copyright restrictions may apply to redistribution; see https://www.ams.org/journal-terms-of-use
1975] J. L. WALSH 47
growing pains due to a rapid increase in membership and in research
publications. It was the period in which the Society created the post of
Executive Director and moved its headquarters to Providence. Also
during this period Walsh served as chairman of the organizing committee
for the International Mathematical Congress, held in Cambridge during
August 1950, the first since World War II. At about this time Walsh was
recipient of a nonmathematical honor—promotion to the rank of captain
in the U.S. Naval Reserve. In his later years Walsh was twice honored by
the dedication of volumes of mathematical journals: SIAM J. (2) 3
(1966) on his seventieth birthday in 1965, and J. Approximation Theory
5 (1972) on his seventy-fifth birthday in 1970.
These mathematical honors were well deserved in view of the quantity
and quality of his original research. Starting with his first publication in
1916, while still an undergraduate, he wrote, singly or jointly with students
and others, a total of 279 research, expository, and book review articles
as well as seven books. Though these papers covered a wide range
of topics, they were, broadly speaking, concerned with four general
areas:
(I) The relative location of the zeros of pairs of rational functions
such as a polynomial and its derivative.
(II) Zeros and topology of extremal polynomials.
(III) The critical points and level lines of Green's function and other
harmonic functions.
(IV) Interpolation and approximation of continuous, analytic, or
harmonic functions.
Regarding the general area (I), this was Walsh's first main research
interest. His doctoral thesis was entitled On the roots of the jacobian, of
two binary forms. It was written under the guidance of Maxime Bôcher
who had proved that if F and G are binary forms of the same degree and
if all the zeros aó of F lie in a circular region A and all the zeros bi of G
lie in a circular region B with BnA = 0, then all the zeros ck of the
jacobian J(F, G) lie in A UB. Like Bôcher, Walsh used geometric and
physical methods, interpreting the ck as equilibrium points in the field
due to positive masses at the points aj and negative masses at the points b$
with an inverse distance force law. Walsh's results are generalizations of the
Lucas theorem that the convex hull of the zeros of a polynomial ƒ contains
all the critical points of/. These results are described in Walsh's papers and
in M. Marden, Geometry of polynomials, 2nd éd., Math Surveys, no. 3,
Amer. Math. Soc, Providence, R.I., 1966, MR 37 #1562. The most
striking of these results are the following three:
(1) If an «th degree polynomial ƒ has nx zeros in a disk \z—c1\^.r1
and the remaining n2=n—n1 zeros in the disk \z—c2|^r2, then any critical
License or copyright restrictions may apply to redistribution; see https://www.ams.org/journal-terms-of-use
48 MORRIS MARDEN [January
point of/ not in one of these disks lies in a third, "average" disk
(2) If Cl9 C2 and C3 are disjoint circular regions and if a rational
function ƒ has in the extended plane all its zeros in CxuC2 and all its
poles in C3, then any critical point off not in C ^ U Q u C , lies in a circular
region C4. The boundary 9C4 of C4 is the locus of the point z4 defined by
the cross ratio (zl9 z2, z3, z4)=const when zl9 z2, z3 vary independently
on the circles dCl9 dC2, dC3 respectively.
(3) Let the form 0(zl 5 z2, • • • , zw) be of degree one in each zi9 and of
total degree n and symmetric in the set zl9 z2, • • • , zn. Let C be a circular
region containing the n points z,=zi0, y = l , 2, • • • , w. Then in C there
exists at least one point £ such that (£, £, • • • , Ç)=$(z10, z20, • • • , zn0).
Regarding the general area (II), the methods and results were suggested
in part by those in area (I). Given a closed bounded set E containing at
least n+\ points and the class Pn of all polynomials z
n+a1z
n~1+- • -+an9
an infrapolynomial p on E means a polynomial p ePn with the property
max \p(z)\ = min max \q(z)\.
zeE «ePn zeE
The zeros of p play a role vis-à-vis set E similar to that of the critical
points of a polynomial ƒ vis-à-vis the zeros of ƒ. For instance, Fejér
proved that the zeros ofp lie in the convex hull of E9 and Fekete showed
that p satisfies a form involving the points of E that is similar to the form
for the logarithmic derivative of ƒ in terms of the zeros of p. Walsh ex-
plored the subject of infrapolynomials intensively in papers which he
published singly or jointly with Fekete, Motzkin, Shisha and Zedek.
Likewise the general area (III) was partly an offshoot of area (I). For
example, Walsh proved that if G is the Green's function (with pole at
infinity) for an unbounded region R with bounded boundary B9 then all
the critical points of G in R lie in the convex hull of B. Thus, the critical
points of G play a role similar to the critical points of a polynomial whose
zeros lie on B. In this connection Walsh also examined in detail the cur-
vature and other characteristics of the level lines of Green's function.
These theorems together with their generalizations to harmonic measures
and other harmonic functions are developed in Walsh's papers and de-
scribed in his book, Critical points of analytical and harmonic functions.
As for general area (IV), the subjects of interpolation and approximation
encompass about half of Walsh's published articles as well as his now
classical treatise entitled Interpolation and approximation. Among his
many original results in this area, probably the most important are the
License or copyright restrictions may apply to redistribution; see https://www.ams.org/journal-terms-of-use
1975] J. L. WALSH 49
following two :
(1) Every function continuous on a bounded Jordan arc J can be ap-
proximated on J uniformly by a polynomial in z.
(2) Every function ƒ analytic in a Jordan region B and continuous on
its closure B can be uniformly approximated on B by a polynomial in z.
The first is a generalization of Weierstrass' theorem, which requires arc
J to be a closed interval of the real axis. The second is a generalization of
Runge's theorem, which requires ƒ to be analytic in B. To prove this
second theorem, Walsh approximated to B by a sequence of Jordan
regions Bn with 5<= Bn+1<^Bn for all n, and then applied Runge's theorem
in B to the function Fn(z)=f(xn(z))9 where w=Xn(
z) maps Bn one-to-one
conformally onto B. Walsh later extended this second theorem to sets B
which are the union of a finite number of disjoint Jordan regions. Thus he
paved the way for the more comprehensive theorem proved later by
Mergelyan: i f / i s a function continuous on any closed bounded set S
and analytic at all interior points of S9 then it can be approximated on
S uniformly by a polynomial in z.
Walsh maintained an active interest in interpolation, approximation and
related topics over a period of about fifty years. Most recently he helped
develop some of the fundamental theorems concerning spline interpolation
and approximation both on the real line and in the complex plane.
His contributions may be found in his published papers as well as in the
monograph The theory of splines and their applications, which he wrote
jointly with J. H. Ahlberg and E. N. Nilson.
In the related area of orthogonal expansions, special mention should
be made of the so-called Walsh functions
SS(*) = .C.
e. On infrapolynomials with prescribed constant term, J. Math. Pures Appl.
(9) 37, 295-316. MR 20 #7098.
1959 a. On extremal approximations, On Numerical Approximation, Univ. of Wiscon-
sin Press, Madison, Wis., pp. 209-216. MR 21 #421.
b. (With T. S. Motzkin), Location of zeros of infrapolynomials, Compositio
Math. 14, 50-70. MR 21 #3539.
c. Approximation on a line segment by bounded analytic functions: Problem (i,
Proc. Amer. Math. Soc. 10, 270-272. MR 21 #6443a.
d. Note on least-square approximation to an analytic function by polynomials, as
measured by a surface integral, Proc. Amer. Math. Soc. 10, 273-279. MR 23
#A1047.
e. Approximation by bounded analytic functions: General configurations, Proc.
Amer. Math. Soc. 10, 280-285. MR 21 #6443b.
f. (With T. S. Motzkin), Polynomials of best approximation on a real finite point
set. I, Trans. Amer. Math. Soc. 91, 231-245. MR 21 #7388.
g. (With H. G. Russell), Integrated continuity conditions and degree of approxima-
tion by polynomials or by bounded analytic functions, Trans. Amer. Math. Soc.
92, 355-370. MR 21 #7311.
h. Note on approximation by bounded analytic functions {Problem a), Math. Z.
72, 47-52. MR 22 #776.
i. (With T. S. Motzkin), Polynomials of best approximation on an interval, Proc.
Nat. Acad. Sci. U.S.A. 45, 1523-1528. MR 22 #9773.
j . Note on invariance of degree of polynomial and trigonometric approximation
under change of independent variable, Proc. Nat. Acad. Sci. U.S.A. 45, 1528—
1533. MR23#A1191.
k. (With H. J. Landau), On canonical conformai maps of multiply connected regions,
Trans. Amer. Math. Soc. 93, 81-96. MR 28 #4093.
1. The analogue for maximally convergent polynomials of JentzscKs theorem,
Duke Math. J. 26, 605-616.
License or copyright restrictions may apply to redistribution; see https://www.ams.org/journal-terms-of-use
60 MORRIS MARDEN [January
1960 a. Solution of the Dirichlet problem for the ellipse by interpolating harmonic
polynomials, J. Math. Mech. 9, 193-196. MR 22 #4891.
b. On the asymptotic properties of extremal polynomials with prescribed constant
term, Math. Z. 73, 339-345. MR 22 #2715.
c. Note on polynomial approximation on a Jordan arc, Proc. Nat. Acad. Sci.
U.S.A. 46, 981-983. MR 22 #12338.
d. On degree of approximation by bounded harmonic functions, J. Math. Pures
Appl. (9) 39, 201-220. MR 27 #1609.
e. (With T. S. Motzkin), Best approximators within a linear family on an interval,
Proc. Nat. Acad. Sci. U.S.A. 46, 1225-1233. MR 28 #5279.
f. Degree of approximation by bounded harmonic functions, Proc. Nat. Acad. Sci.
U.S.A. 46, 1390-1393. MR 22 #12338b.
g. Note on degree of approximation by bounded analytic functions: Problem p,
Trans. Amer. Math. Soc. 96, 246-258. MR 22 #11140.
1961 a. The circles of curvature of the curves of steepest descent of Green's function,
Amer. Math. Monthly 68, 323-329. MR 23 #A3272.
b. (With T. S. Motzkin), Conformai maps of small disks, Proc. Nat. Acad. Sci.
U.S.A. 47, 1838-1843. MR 26 #307.
c. (With O. Shisha), The zeros of infrapolynomials with some prescribed coef-
ficients, J. Analyse Math. 9, 111-160. MR 25 #174.
d. (With J. P. Evans), Approximation by bounded analytic functions to functions
represented by Dirichlet series, Proc. Amer. Math. Soc. 12, 875-879. MR
25 #4109.
e. A new generalization of Jensen's theorem on the zeros of the derivative of a poly-
nomial, Amer. Math. Monthly 68, 978-983. MR 24 #A2009.
1962 a. Degree of polynomial approximation to an analytic function as measured by a
surface integral, Proc. Nat. Acad. Sci. U.S.A. 48, 26-32. MR 24 #A2176.
b. (With J. H. Ahlberg and E. N. Nilson), Best approximation properties of the
spline fit, J. Math. Mech. 11, 225-234. MR 25 #738.
c. Asymptotic properties of polynomials with auxiliary conditions of interpolation,
Ann. Polon. Math. 12, 17-24. MR 27 #1605.
d. (With T. S. Motzkin), Polynomials of best approximation on an interval. II,
Proc. Nat. Acad. Sci. U.S.A. 48, 1533-1537. MR 26 #2788.
e. On the convexity of the ovals of lemniscates, Studies in Mathematical Analysis
and Related Topics, Stanford University Press, Stanford, Calif., pp. 419-423.
MR 27 #1606.
f. Approximation par les fonctions holomorphes bornées. Problème $', J. Math.
Pures Appl. (9) 41, 213-232. MR 27 #5914.
1963 a. (With T. S. Motzkin), Zeros of the error function for Tchebycheff approximation
in a small region, Proc. London Math. Soc. (3) 13, 90-98. MR 26 #1667.
b. Restricted infrapolynomials and trigonometric infrapolynomials, Proc. Nat.
Acad. Sci. U.S.A. 49, 302-304. MR 27 #2613.
c. A generalization of Fejér's principle concerning the zeros of extremal polynomials,
Proc. Amer. Math. Soc. 14, 44-51. MR 27 #271.
d. A sequence of rational functions with application to approximation by bounded
analytic functions, Duke Math. J. 30,177-189. MR 30 #2155.
e. (With O. Shisha), The zeros of infrapolynomials with prescribed values at given
points, Proc. Amer. Math. Soc. 14, 839-844. MR 27 #3785.
f. Note on the convergence of approximating rational functions of prescribed type,
Proc. Nat. Acad. Sci. U.S.A. 50, 791-794. MR 28 #400; 28 #1247.
g. (Book Review), Analytic function theory, by E. Hille, SIAM Rev. 5, 377-378.
License or copyright restrictions may apply to redistribution; see https://www.ams.org/journal-terms-of-use
19751 J. L. WALSH 61
1964 a. Padé approximants as limits of rational functions of best approximation, J.
Math. Mech. 13, 305-312. MR 28 #4283.
b. (With O. Shisha), On the location of the zeros of some infrapolynomials with
prescribed coefficients, Pacific J. Math. 14, 1103-1109. MR 30 #232.
c. (With O. Shisha), Extremal polynomials and the zeros of the derivative of a
rational function, Proc. Amer. Math. Soc. 15, 753-758. MR 29 #4876.
d. The convergence of sequences of rational functions of best approximation, Math.
Ann. 155, 252-264. MR 29 #1484.
e. A theorem of Grace on the zeros of polynomials, revisited, Proc. Amer. Math.
Soc. 15, 354-360. MR 28 #4092.
f. (With Z. Rubinstein), On the location of the zeros of a polynomial whose center
of gravity is given, J. Analyse Math. 12, 129-142. MR 29 #4877.
g. (With A. Sharma), Least squares and interpolation in roots of unity, Pacific
J. Math. 14, 727-730. MR 28 #5278.
h. Surplus free poles of approximating rational functions, Proc. Nat. Acad. Sci.
U.S.A. 52, 896-901. MR 30 #3983.
i. (With Maynard Thompson), Approximation with auxiliary conditions, J. Math.
Mech. 13, 1015-1019. MR 30 #1253.
j . The location of the zeros of the derivative of a rational function, revisited,
J. Math Pures Appl. (9) 43, 353-370. MR 31 #3582.
1965 a. Geometry of the zeros of the sums of linear fractions, Trans. Amer. Math.
Soc. 114, 30-39. MR 31 #3579.
b. (With J. H. Ahlberg and E. N. Nilson), Fundamental properties of generalized
splines, Proc. Nat. Acad. Sci. U.S.A. 52, 1412-1419. MR 36 #6846.
c. (With J. H. Ahlberg and E. N. Nilson), Best approximation and convergence
properties of higher-order spline approximations, J. Math. Mech. 14, 231-243.
MR 35 #5823.
d. (With A. Sinclair), On the degree of convergence of extremal polynomials and
other extremal functions, Trans. Amer. Math. Soc. 115, 145-160. MR 33
#7564.
e. The convergence of sequences of rational functions of best approximation. II,
Trans. Amer. Math. Soc. 116, 227-237. MR 32 #6120.
f. (With J. H. Ahlberg and E. N. Nilson), Extremal, orthogonality, and conver-
gence properties of multidimensional splines, J. Math. Anal. Appl. 12, 27-48.
MR 37 #661.
g. (With J. H. Ahlberg and E. N. Nilson), Convergence properties of generalized
splines, Proc. Nat. Acad. Sci. U.S.A. 54, 344-350. MR 36 #6847.
h. Hyperbolic capacity and interpolating rational functions, Duke Math. J. 32,
369-379. MR 31 #6081.
i. The convergence of sequences of rational functions of best approximation with
some free poles, Approximation of Functions (Proc. Sympos. General Motors
Res. Lab., 1964), Henry L. Garabedian, Ed., Elsevier, Amsterdam, 1965,
pp. 1-16. MR 32 #4441.
1966 a. (With T. S. Motzkin), Mean approximation on an interval for an exponent less
than one, Trans. Amer. Math. Soc. 122, 443-460. MR 34 #1769.
b. Approximation by polynomials: Uniform convergence as implied by mean con-
vergence, Proc. Nat. Acad. Sci. U.S.A. 55, 20-25. MR 32 #5891.
c. Approximation by polynomials: Uniform convergence as implied by mean con-
vergence, II. Proc. Nat. Acad. Sci. U.S.A. 55, 1405-1407. MR 35 #4443.
d. (With H. G. Russell), Hyperbolic capacity and interpolating rational functions.
II, Duke Math. J. 33, 275-279. MR 33 #1624.
License or copyright restrictions may apply to redistribution; see https://www.ams.org/journal-terms-of-use
62 MORRIS MARDEN [January
e. The convergence of approximating rational functions of prescribed type, Con-
temporary Problems in the Theory of Analytic Functions (M. A. Lavrent'ev,
Ed.), Proc. Internat. Conference on the Theory of Analytic Functions
(Erevan, 1965), "Nauka", Moscow, 1966, pp. 304-308. (Russian). MR 35
#3069.
f. Approximation by polynomials: Uniform convergence as implied by mean
convergence. I l l , Proc. Nat. Acad. Sci. U.S.A. 56, 1406-1408. MR 35 #4444.
1967 a. Best approximation by rational functions and by meromorphic functions with
some free poles, J. Analyse Math. 18, 359-375. MR 36 #1673.
b. On the convergence of sequences of rational functions, SIAM J. Numer. Anal.
4, 211-221. MR 36 #1675.
c. An extension of the generalized Bernstein lemma, Colloq. Math. 16, 91-92.
MR 35 #6844.
d. (With J. H. Ahlberg and E. N. Nilson), Complex cubic splines, Trans. Amer.
Math. Soc. 129, 391-413. MR 36 #573.
1968 a. Degree of approximation by rational functions and polynomials, Michigan Math.
J. 15, 109-110. MR 36 #6845.
b. Note on classes of functions defined by integrated Lipschitz conditions, Bull.
Amer. Math. Soc. 74, 344-346. MR 36 #2807.
c. (With T. S. Motzkin), A persistent local maximum of the pth power deviation
on an interval,p<\, Pacific J. Math. 24, 133-142. MR 38 #4868.
d. The convergence of sequences of rational functions of best approximation. Ill,
Trans. Amer. Math. Soc. 130, 167-183. MR 36 #1674.
e. Approximation by bounded analytic functions: Uniform convergence as implied
by mean convergence, Trans. Amer. Math. Soc. 130, 406-413. MR 36 #3997.
f. (With J. H. Ahlberg and E. N. Nilson), Cubic splines on the real line, J. Approxi-
mation Theory 1, no. 1, 5-10. MR 37 #6650.
1969 a. (With E. B. Saff), Extensions of D. Jackson's theorem on best complex poly-
nomial mean approximation, Trans. Amer. Math. Soc. 138, 61-69. MR 39
#3001.
b. Inequalities expressing degree of convergence of rational functions, J. Approxi-
mation Theory 2, 160-166. MR 39 #7115.
c. (With J. H. Ahlberg and E. N. Nilson), Properties of analytic splines. I. Com-
plex poly nominal splines, J. Math. Anal. Appl. 27, 262-278. MR 42 #8136.
d. Note on approximation by bounded analytic functions, Problem a: General
configurations, Aequationes Math. 3, 160-164. MR 41 #5632.
e. Approximations to a function by a polynomial in a given function, Amer. Math.
Monthly 76, 1049-1050.
f. (With Z. Rubinstein), Extensions and some applications of the coincidence
theorems, Trans. Amer. Math. Soc. 146, 413-427. MR 40 #4428.
1970 a. (With W. J. Schneider), On the shape of the level loci of harmonic measure,
J. Analyse Math. 23, 441-460. MR 42 #6205.
b. Approximation by rational f unctions : Open problems, J. Approximation Theory
3, 236-242. MR 43 #538.
c. Note on degree of convergence of sequences of rational functions of prescribed
type, Proc. Nat. Acad. Sci. U.S.A. 67, 1188-1191. MR 42 #4748.
1971 a. (With J. H. Ahlberg and E. N. Nilson), Complex polynomial splines on the
unit circle, J. Math. Anal. Appl. 33, 234-257. MR 43 #3696.
b. (With Dov Aharonov), Some examples in degree of approximation by rational
functions, Trans. Amer. Math. Soc. 159, 427-444. MR 44 #6974.
License or copyright restrictions may apply to redistribution; see https://www.ams.org/journal-terms-of-use
19751 J. L. WALSH 63
c. Mean approximation by polynomials on a Jordan curve, J. Approximation
Theory 4, 263-268. MR 45 #3726.
1972 a. (With Dov Aharonov), On the convergence of rational functions of best approxi-
mation to a meromorphic function, J. Math. Anal. Appl. 40, 418-426. MR 47
#5263.
b. (With Myron Goldstein), Approximation by rational functions on Riemann
surfaces, Proc. Amer. Math. Soc. 36, 464-466. MR 47 #2072.
c. Note on the convergence of sequences of rational functions, Proc. Nat. Acad.
Sci. U.S.A. 69, 2963-2964. MR 46 #7522.
1973 a. (With T. S. Motzkin), Equilibrium of inverse distance forces in three dimensions,
Pacific J. Math. 44, 241-250. MR 47 #5234.
b. (With E. B. Saflf), On the convergence of rational functions which interpolate
in the roots of unity, Pacific J. Math. 45, 639-641.
c. History of the Riemann mapping theorem, Amer. Math. Monthly 80, 270-276.
1974 a. The role of the pole in rational approximation, Rocky Mountain Math. J.
(to appear),
b. (With P. M. Gauthier and Alice Roth), Uniform approximation in the spherical
metric (in preparation).
BOOKS BY JOSEPH L. WALSH
1. Approximation by Polynomials in the Complex Domain, Mémorial des Sciences
Mathématiques, Gauthier-Villars, Paris, 1935, ii+72 pp.
2. Interpolation and Approximation by Rational Functions in the Complex Domain,
Colloquium Publications, Vol. 20, American Mathematical Society, Providence, R.I.,
1935, ix-f382pp.; 2nd edition, 1952; 3rd edition, 1960; 4th rev. edition, 1965;
5th edition, 1969; Russian translation, IL, Moscow, 1961. MR 36 #1671; 1672b, c.
3. A Bibliography on Orthogonal Polynomials (with J. A. Shohat and Einar Hille),
National Research Council, Bulletin No. 103, Washington, D.C., 1940, ix+204 pp.
4. The Location of Critical Points of Analytic and Harmonic Functions, Colloquium
Publications, Vol. 34, American Mathematical Society, Providence, R.I., 1950,
viii+384pp. MR 12, 249.
5. Approximation by Bounded Analytic Functions, Mémorial des Sciences Mathé-
matiques, Fase. 144, Gauthier-Villars, Paris, 1960, 66 pp. MR 22 #9770.
6. A Rigorous Treatment of Maximum-Minimum Problems in the Calculus, D. C. Heath,
Boston, Mass., 1962, 22 pp.
7. The Theory of Splines and Their Applications, (with J. H. Ahlberg and E. N. Nilson),
Academic Press, New York and London, 1967, xi+284 pp. MR 39 #684.
WALSH'S P H . D . STUDENTS
(With journal reference to some or all their thesis results)
1928 MORRIS MARDEN, On the location of the roots of the jacobian of two binary
forms and of the derivative of a rational function, Trans. Amer. Math. Soc. 32
(1930), 81-109.
1930 ORIN J. FARRELL, On the expansion of harmonic f unctions in series of harmonic
polynomials belonging to a simply connected region, Amer. J. Math. 57 (1935).
1931 CECIL T. HOLMES, Approximation of harmonic functions in 3 dimensions by
harmonic polynomials (not published).
License or copyright restrictions may apply to redistribution; see https://www.ams.org/journal-terms-of-use
64 MORRIS MARDEN [January
1932 JOSEPH L. DOOB, Boundary values of analytic functions, Trans. Amer. Math.
Soc. 34 (1932), 153-170; ibid 35 (1933), 418-451; On a theorem of Gross and
Iversen, Ann. of Math. 33 (1932), 753-757.
1932 HELEN G. RUSSELL, On the convergence and overconvergence of sequences of
polynomials of best simultaneous approximation to several functions analytic in
distinct regions, Trans. Amer. Math. Soc. 36 (1934), 13-28.
1935 JOHN H. CURTISS, Interpolation in regularly distributed points, Trans. Amer.
Math. Soc. 38 (1935), 458-473; On the Jacobi series, Trans. Amer. Math. Soc.
49 (1941), 467-501. MR 2, 355.
1935 YU-CHENG SHEN, On interpolation and approximation by rational functions
with preassignedpoles, J. Chinese Math. Soc. 1 (1936), 154-173.
1936 WALTER E. SEWELL, Generalized derivatives and approximation by polynom-
ials, Trans. Amer. Math. Soc. 41 (1937), 84-120.
1937 ZEHMAN I. MOSESSON, Maximal sequences of polynomials (not published).
1938 FLOYD E. ULRICH, Problem of type for a certain class of Riemann surfaces,
Duke Math. J. 5 (1939), 567-589. MR 1, 8.
1940 MAURICE H. HEINS, Extremal problems for functions analytic and single-
valued in a doubly-connected region, Amer. J. Math. 62 (1940), 91-106. MR 1,
114; On the iteration of functions which are analytic and single-valued in a given
multiply-connected region, Amer. J. Math. 63 (1941), 461-480. MR 2, 275.
1940 ABRAHAM SPITZBART, Approximation in the sense of least pth powers with a
single auxiliary condition of interpolation, Bull. Amer. Math. Soc. 52 (1946),
338-346. MR 7, 425.
1941 EDWIN N. NILSON, Interpolation and approximation of analytic functions by
functions analytic and bounded in a given region-, Interpolation and approximation
by functions analytic and bounded in a given region', (published with J. L. Walsh),
Trans. Amer. Math. Soc. 55 (1944), 53-67; MR 5, 115; ibid. 65 (1949), 239-
258. MR 10, 524.
1942 LYNN H. LOOMIS, The radius and modulus of n-valence for analytic functions
where first n—\ derivatives vanish at a point, Bull. Amer. Math. Soc. 46 (1940),
496-501. MR 1, 308; On an inequality of Seidel and Walsh, 48 (1942), 908-911.
MR 5, 37.
1947 IVAN R. HERSHNER, Jr., Radii ofunivalence andp-valence of functions analytic
in the unit circle (not published).
1948 H. MARGARET ELLIOTT, On the degree of approximation to harmonic func-
tions by harmonic polynomials, Trans. Amer. Math. Soc. 67 (1949), 381-420.
1949 HELLEN KELSALL NICKERSON, Studies in overconvergence, Bull. Amer.
Math. Soc, 55 (1949), 1061.
1952 ALAN F. KAY, Distribution of zeros of sequences of polynomials of unbounded
degree, Proc. Amer. Math. Soc. 6 (1955), 571-582. MR 17, 247.
1952 ISAAC E. BLOCK, Kernel functions and class L2, Proc. Amer. Math. Soc. 4
(1953), 110-117. MR 14, 989; Duke Math. J. 19 (1952), 367-378. MR 14, 153.
1953 THEODORE J. RIVLIN, On sufficient conditions for overconvergence, Proc.
Amer. Math. Soc. 6 (1955), 597-602. MR 17, 138.
1953 LAWRENCE ROSENFELD, On the boundary of a conformai map, Trans.
Amer. Math. Soc. 81 (1956), 49-73.
1953 JACQUELINE P. EVANS, On approximation and interpolation by functions ana-
lytic in a given region and an application to orthonormal systems, Arch. Math. 5
(1954), 191-196; Proc. Nat. Acad. Sci. U.S.A. 40 (1954), 332-337; Trans. Amer.
Math. Soc. 79 (1955), 158-172; Proc. Amer. Math. Soc. 7 (1956), 1085-1090.
License or copyright restrictions may apply to redistribution; see https://www.ams.org/journal-terms-of-use
19751 J. L. WALSH 65
1954 RICHARD S. VARGA, Semi-infinite and infinite strips of zeros, Univ. e Poli-
tccnio Torino, Rend. Sem. Math. 11 (1951/52), 289-296. MR 14 #546.
1956 MISHAEL ZEDEK, On generalized Tchebycheff polynomials, Proc. Nat.
Acad. Sci. U.S.A. 42 (1956), 99-104.
1957 HENRY J. LANDAU, On canonical conformai maps of multiply connected
domains, Trans. Amer. Math. Soc. 99 (1961), 1-20. MR 22 #12212.
1961 VINCENT C. WILLIAMS, On conformai maps of regions of infinite connectivity,
Trans. Amer. Math. Soc. 155 (1971), 427-453.
1962 DOROTHY B. SHAFFER, Shape of level loci of Green's function and other
harmonic functions, J. Analyse Math. 17 (1966), 59-70; J. Math. Mech. 19
(1969), 41-48.
1963 VICTOR M. MANJARREZ, Polynomial bases for compact sets in the plane,
Trans. Amer. Math. Soc. 132 (1968), 541-551.
1964 JERRY L. FIELDS, Rational approximations to hypergeometric functions,
Math. Comp. 19 (1965), 606-624.
1968 EDWARD B. SAFF, Interpolation and functions of class H(k, a, 2), J. Approxi-
mation Theory 1 (1968), 488-492. MR 39 #2992; Trans. Amer. Math. Soc.
138 (1969), 61-69; ibid 141 (1969), 79-92. MR 39 #4406.
1973 MARVIN E. ORTEL, Approximation by bounded analytic functions.
Current address: Department of Mathematics, University of Wisconsin, Milwaukee,
Wisconsin 53201
License or copyright restrictions may apply to redistribution; see https://www.ams.org/journal-terms-of-use