P. I. Trofimov. A contribution to the theory of finite factorizable groups . . . 522
A. J. Khelemskii. A certain analytic condition for the radical of Banach’s commutative algebra, and related decomposability problems . . . 525
A. V. Chernavskii. Singular points of topologic imbeddings of manifolds and unification of locally plane cells . . . 528
C. A. Chunikhin. Indexials and normalizers . . . 531
L. A. Shemetkov. Normal structure of finite groups . . . 534

CYBERNETICS AND THE REGULATION THEORY

Iu. P. Leonov. Asymptotically optimal systems simulating the process of control learning . . . 538

MECHANICS

N. N. Krasovskii. Approximation of a problem on optimal control in a system with aftereffect . . . 540

THEORY OF ELASTICITY

L. A. Galin, G. P. Cherepanov. Self-supporting failure of a stressed brittle body . . . 543

PHYSICS

M. P. Vaniukov, O. D. Dmitrievskii, V. I. Isaenko, V. A. Serebriakov. A rapid liquid seal for the modulation of the optical quantum generator quality factor on neodymium glass . . . 547
V. I. Gol’danskii. On the β⁺-decay of neutron deficient isotopes . . . 549
L. V. Dubovoi, V. P. Fediakov. On the confinement of hightemperature plasma in a trap with magnetic mirrors . . . 553
V. N. Lebedeva, G. I. Distler, B. N. Grechushnikov. Optical anisotropy of metallic textures . . . 556
T. A. Poluektov, Iu. M. Popov. The influence of a strong magnetic field on the recombination radiation in semiconductors . . . 559

TECHNICAL PHYSICS

S. R. Grigorova, D. M. Tolstoi. Resonance fall of frictional force . . . 562

CRYSTALLOGRAPHY

A. G. Kapyshev, V. V. Ivanova, Iu. N. Venevtsev. New perovskites . . . 564
Li Te-yü, V. I. Simonov, N. V. Belov. The crystal structure of niocalite . . . 566

ERRATA

In the article by A. M. Globus, “The influence of weight, structure, and the nature of the surface of the solid phase on the redistribution of moisture in closed disperse systems under the action of a temperature gradient,” published in DAN, vol. 160, No. 1, 1965, the quantities \(W_n\) plotted along the abscissa axis are expressed: in Fig. 1, as percentages by weight, and in Fig. 2, as percentages by volume of the medium under study. The formula on p. 84, line 14, should read:

\[ \nu = (0.76 + 5.93\,a)\cdot 10^{-7}\ \mathrm{g}\cdot \mathrm{cm}^{2}\cdot \mathrm{sec}^{-1}. \]

In the article by A. V. Ivanov, “Density near the front critical point of a submerged body flowing around by a supersonic stream of rarefied gas,” published in DAN, vol. 161, No. 2, 1965, the following correction must be made: on p. 317, line 18, where it is printed \(\lambda_s = 2\) mm, it should read \(\lambda_s = 0.2\) mm.

In my article (V. I. Shevchenko, “On a boundary-value problem for a vector holomorphic in a half-space”), published in DAN, vol. 154, No. 2, 1964, on p. 278, line 21, where it is printed: “By virtue of condition (7) there will be found such angles...,” it should read: “Suppose that there are found such discontinuous angles...” and so on. This assumption should be included in the statement of the theorem.

Let us note that the theorem is also true without this additional assumption.

T. — 03816 Signed for printing 22/II—1966. Print run 1375 copies. Order 10
Paper size 70 × 108 1/16 Printed sheets 21.0 + 2 inserts. Paper sheets 7½ Publisher’s accounting sheets 21.8
2nd Printing House of the Publishing House “Nauka,” Moscow, Shubinskii Lane, 10