The symbol: w+1. This is the smallest ordinal number after "omega". Informally we can think of this as infinity plus one. One formulation of ordinals is to treat them as sets of all smaller ordinals. In order to say omega and one is "larger" than "omega" we define largeness to mean that one ordinal is larger than another if the smaller ordinal is included in the set of the larger. The set w+1 would be {w,0,1,2,3,...}. It would be composed of all the non-negative integers plus omega. Thus w+1 by this definition is larger. However, since the cardinality of every ordinal is represented by the cardinality of it's set, we can also show that in a sense w = w+1, since w={0,1,2,3,...} and w+1={w,0,1,2,...} we can pair off arguments as: {(0,w),(1,0),(2,1),(3,2),...}, which shows both sets have the same number of elements, even though w+1 includes one more. Confused? Basically there is two ways to look at comparison of infinities: the cardinal view and the ordinal view. By the ordinal view, omega and one is greater, by the cardinal view omega and omega plus one are the same thing. Cardinals don't play a large role in googology, but the countable ordinals do. So for our purposes the distinction between w and w+1 is important. (I copied this off a google site)
by SauceQuest31 December 29, 2022