对于结论不确定的问题称为存在型问题 ,在数学命题中常以适合某种性质的结论“存在”、“不存在”、“是否存在”等形式出现 .“存在”就是有适合某种条件或符合某种性质的对象 ,对于这类问题无论用什么方法 ,只要找出一个 ,就说明存在 .“不存在”一般需推理论证 ,常用反证法 The problem of inconclusive conclusions is called existence-type problem. In mathematics propositions, the form of “existence”, “non-existence”, “existence”, etc. often appears in a form suitable for a certain nature. “Existence” means that there is a condition suitable or Objects that meet certain properties, no matter what method is used for such problems, as long as one is found, it means existence. “Absence” generally requires theoretical evidence, commonly used anti-evidence method