Nam Hung Tran Nguyen

1. "Small category" is small??    A category is small if the class of its object forms a set . For example, the category of set is NOT  a small category since the collection of all sets is not a set by a well-known paradox. As a result, the category of topological spaces  is also not a set because it must be "bigger" than the category of set, since sets only differ in elements, but topological spaces differ in elements and open/closed (sub)sets.    This might contradict with our usual sense about small/large things, because sets are often so big that we find it hard to control them. But category theory has reached another level, where set might be regarded as the "simpliest" structure/level.  2. "Constant" simplicial set    From our usual sense, "constant" means some stuff should be fixed and invariant of the variables/factors involved. Meanwhile, a constant simplicial set is defined in a very special way: it is the category in which th...

Here is a collection of interesting facts about the language of Vietnamese (tiếng Việt) that I just found out when talking to my friends, who are all Europeans, in Bonn (Germany).  1. In Vietnamese, grandson and nephew are called the same (cháu trai). Similarly, granddaughter and niece are also called the same (cháu gái).  2. In Vietnamese, you can use the same pronoun "em" to call your younger sibling, no matter whether it is your younger brother or your younger sister. Similarly, this pronoun can be used to call someone who is just a few years younger than you, no matter whether this person is a man or a woman.  3. However, when referring to your older sibling, you must use the pronoun "anh" to call your older brother and the pronoun "chị" to cold your older sister. Similarly, you can use the pronoun "anh" to call a boy who is just a few years older than you and the pronoun "chị" to call a girl who is just a few years older than you. ...