当且仅当

It is proved that a complete lattice is completely distributive lattice if and only if it is both semi-Smooth lattice and semi-continuous lattice.

证明了完备格L是半Smooth格和半连续格当且仅当L是完全分配格。

As an application, it is proved that a continuous map of an interval is chaotic iff it is distributively chaotic in a sequence.

给出紧度量空间上连续映射按序列分布混沌的一个充分条件，并证明区间连续自映射是混沌的当且仅当它是按某序列分布混沌的。

The concept of a consistent term structure is introduced and a result on its existence is proved with the theory of convex analysis.

在引入相容的期限结构概念后，利用凸分析理论给出了它的一个存在性结果：存在相容的期限结构当且仅当市场是无套利的。

The problem of finding stabilizer quantum-error-correcting codes can be transformed into the problem of finding classical self-orthogonal linear codes over the Galois field GF(4) under a Hermitian inner product. A classical cyclic code over the field GF(4) is self-orthogonal with respect to the Hermitian inner product iff the generator polynomial of its dual code is a factor of its generator polynomial.

寻找量子稳定子码的问题可以转化为寻找GF(4)上厄米内积自正交的经典线性码的问题；对于GF(4)上的经典循环码，它是厄米内积自正交的，当且仅当它的对偶码的生成多项式是其生成多项式的因子。

Methods Firstly,by definition it is proved that the minimality of a set is equivalent to the condition that the orbit of every point is dense in that set.

方法首先，利用定义证明一集合是极小的当且仅当每一点的轨道在该集合中稠密。

This paper investigates topological properties of the general gradient system, and demonstrates by results of differential topology that the boundedness of the general gradient system is equivalent to the boundedness of the potential energy boundary surface. Moreover, a general gradient system is bounded if, and only if the system has both sink point and source point.

该文研究了广义梯度系统的拓扑性质，应用微分拓扑学原理证明，广义梯度系统的完全稳定性与势能界面的有界性是等价的；广义梯度系统完全稳定当且仅当该系统既有渊点又有源点。

When the consistency is checked, the "distance diagram"is employed. It is concluded that the axioms of a description satisfies the consistency iff there are no negative directed cycles in the distance diagram.

在验证ISITL描述的一致性时采用"距离矢量图"，并认为一个ISITL描述满足一致性当且仅当其距离矢量图上不存在负矢量和的有向回路。

Tu is a digraph denoted as DHG with nodes corresponding to the data segments of P and a set of directed arcs joining these nodes such that ,for i≠j,Di→Dj Iff there exist tTu s.t.

Dn.A数据库的P wrtTu层次图划分为华赋性与节点对应的数据段P和直接参与了这些节点的弧集，这样，因为我≠，邸→当且仅当存在tεTus.t。

A finite distributive lattice is called a matchable distributive lattice if and only if there exists a plane weakly elementary bipartite graph such that.

一个有限分配格L称为匹配分配格当且仅当存在一个平面弱基本二部图G使得ML。

Then R is a division ring if only if R is a left uniform ring.

则R是除环当且仅当R是左一致环。

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。