This provides simplicity but still retains the advantages of compactness. The main advantages of integrated graphics include cost, compactness, simplicity and low energy consumption. Examples of such properties include connectedness, compactness, and various separation axioms. Various definitions of compactness may apply, depending on the level of generality. The finiteness of the formula 23s ensures the compactness of formula 26. The language of covers is often used to define several topological properties related to "compactness". In 1936 Maltsev proved the compactness theorem. In particular, projective spaces satisfy a condition called properness which is analogous to compactness. It also requires compactness and convexity of the set. He also designs and modifies his own rebreathers to increase their compactness and efficiency. In first-countable spaces, sequential compactness and countable compactness are equivalent properties. The compactness and low silhouette of the vehicle are generally advantages on a battlefield. The resulting NXT programs have the compactness and clarity offered by that programming environment. The relative compactness of telescopic booms makes them adaptable for many mobile applications. This advantage of compactness comes with some disadvantages.