摘要:

An antichain of subsets of 1,2,...,nhas the Erdös‐Ko‐Rado property if |Ai|⩽n/2 andAi∩Aj≠Ø(i=j). This paper contains a number of results concerning the distribution of sizes of sets in such a family, and also in families where the restriction |Ai|⩽n

ISSN:0022-2526    

DOI:10.1002/sapm19765511

年代:1976

数据来源: WILEY

摘要:

The one‐dimensional form of the three‐wave resonant interaction, for bounded envelopes, is solved exactly by an inverse scattering transform, which was originally suggested by Zakharov and Manakov. In addition to solving a third‐order inverse scattering problem, we show how to solve this more complicated third‐order three‐wave problem in terms of three simpler second‐order problems. The general result is that during the interaction, all solitons contained in the envelope of the wave with the middle group velocity will “split,” and be added to the original number of solitons contained in both the fast and slow envelopes. These results are then applied to the “decay” and “explosive” instabilities of plasmas, and necessary and sufficient conditions are found for exciting the explosive instability in the

ISSN:0022-2526    

DOI:10.1002/sapm19765519

年代:1976

数据来源: WILEY

摘要:

The plane mixing layer between two streams of different densities and velocities is studied using a complete, phenomenological model of turbulence. The model is an extension of that described by Saffman [11]. The properties of similarity solutions are computed, and compared with experimental data. The qualitative dependence on velocity ratio, density ratio, compressibility and adverse pressure gradient is predicted correctly. The quantitative agreement is satisfactory.

ISSN:0022-2526    

DOI:10.1002/sapm197655145

年代:1976

数据来源: WILEY

摘要:

An extension of the minimal convective system of Lorenz, Howard and Malkus to three‐dimensional motions in an electrically conducting fluid is presented. It is shown that at conditions relevant to the sun this system exhibits linearly stable periodic solutions with a non‐zero magnetic field, which are suggestive of dynamo act

ISSN:0022-2526    

DOI:10.1002/sapm197655165

年代:1976

数据来源: WILEY

摘要:

It is well known that one can construct an infinite sequence on three or more symbols such that no two consecutive blocks are identical. In this paper we give a combinatorial characterization for those finite sequences which are maximal in the sense that appending to them even one more symbol yields two consecutive identical blocks.

ISSN:0022-2526    

DOI:10.1002/sapm197655183

年代:1976

数据来源: WILEY

摘要:

Let 〈d1,d2,...,dp,〉 be a realizable degree sequence,di⩾2; then a graphGcan be constructed so that deg(viand so that fori≠j, the number of edge‐disjoint paths betweenviandvji

ISSN:0022-2526    

DOI:10.1002/sapm197655187

年代:1976

数据来源: WILEY