What is Decidability theory?
'''Decidability theory''' is a branch of [[mathematics]]. Suppose there is a [[set]], and there is an element. There is also an [[algorithm]]. The algorithm will simply check if the element belongs to the set or not. If the algorithm stops (after a limited time) and has reached a decision, if the element is in the set or not, this is called '''decidable'''. In simple terms, if there is a shopping bag, '''decidability''' is that one is able to check whether or not there is some [[salad]] in the bag. Some logical problems cannot be decided that way (''This statement is false''). They are called '''undecidable''' There is a weaker property too, called '''semidecidable'''. A set is called semidecidable (or recursively enumerable), if there is an algorithm that lists its elements out.{{cn}} {{Mathematical logic}} {{Set theory}} {{Math-stub}} [[Category:Theoretical computer science]] [[Category:Decision theory]]