查询词典 if and only if

A linear mapping between two Banach spaces and is continuous if and only if its graph is a closed subset of.

巴拿赫空间之间的线性映射是连续的，当且仅当这个映射的图像是闭集合。

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。

For example, one of our conclusions is that a nonsingular QSIC has one affinely finite component if and only if the characteristic equation of the two quadrics has two distinct real roots and a pair of complex conjugate roots.

由于两二次曲面的特征方程实根个数及其重数可用精确的计算方法得到，本文分类结果可用于实现对任意两二次曲面的非平面交线拓扑形态的判断。

In the third section,we study the relationship between the APOTP for continuous map / on a compact metric space X and that for the lift map / of / on a covering space X and show that has the APOTP if and only if has the APOTP.

在第四节中，我们研究逆极限空间上移位映射的APOTP，讨论紧致度量空间上连续映射APOTP与逆极限空间上移位映射APOTP间的关系。

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。

Gdel's second incompleteness theorem can be stated as follows: For any formal effectively generated theory T including basic arithmetical truths and also certain truths about formal provability, T includes a statement of its own consistency if and only if T is inconsistent .

第二，他证明了，对于任意的数学系统，如果其中包含了算术系统的话，那么我们不能在这个系统内部证明它的一致性。这就是希尔伯特第二问题答案的一部分。

The growth of functions in these spaces depends on a weighted function ρ. We investigate the relation between growth and boundary values of the functions, and prove that a function or its radial derivative is in one of the spaces if and only if the p'integral average of the difference of its boundary value function is integrable or bounded.

研究这些函数空间中函数的增长性与边界值的关系，得到了函数或其径向导数属于相应空间的充分必要条件是其边界值差分的p次积分平均应具备一定的可积性或有界性。

Theorem Let M be a orientable or non-orientable closed surface, and f a C°-flow whose every singular point is isolated. Then f has POTP if and only if the following three conditions hold

定理 设M是任一个可定向或不可定向的闭曲面，f是M上任一个奇点均孤点的C〓-流，则f具有伪轨跟踪性质的充分必要条件是

In this paper a new necessary and sufficient condition of graphic isomorphism is proved which is stated as following: two graphs are isomorphic if and only if their subgraphs are isomorphic and the new vertices as well as their adjancy edges are corresponding with the property of isomorphism.

提出了一个新的判定图同构的充分必要条件，即在子图同构的前提下，根据新增顶点及相应关联边的关系，判断母图同构的充分必要条件。

And then the definition of simply complete Lie colour algebra and L self-homomorphism are given .A Lie colour algebra is simply complete if and only if it can not be decomposed .

然后给出了单完备李color代数的定义，并给出了一个李color代数是单完备的充要条件，即是不可分解的，同时引入了L的L自同态的定义。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。