منابع مشابه
Suslin Lattices
In their work on spreading models in Banach spaces, Dilworth, Odell, and Sari [4] introduced the notion of a Suslin lower semi-lattice, a seemingly slight weakening of the notion of a Suslin tree. They posed several problems of a set theoretic nature regarding their notion. In this paper, we make a systematic study of the notion of Suslin lower semi-lattice, answering some of the questions rais...
متن کاملSuslin Sets
Proof. Suppose z is in the RHS. Then, for some f ∈ Y X , z ∈ Sxfx for all x ∈ X. Hence for each x ∈ X there is y = fx so that z ∈ Sxy, so z is in the LHS. Suppose z is in the LHS. Then for each x ∈ X there is some y ∈ Y so that z ∈ Sxy. Hence for each x ∈ X the set Tx = { y : z ∈ Sxy } is not empty. By AC there is a function f ∈ Y x so that, for all x ∈ X, fx ∈ Tx. Hence, for all x ∈ X, z ∈ Sxf...
متن کاملFree pre-Lie algebras are free as Lie algebras
We prove that free pre-Lie algebras, when considered as Lie algebras, are free. Working in the category of S-modules, we define a natural filtration on the space of generators. We also relate the symmetric group action on generators with the structure of the anticyclic PreLie operad.
متن کاملFree Algebras in Varieties
We define varieties of algebras for an arbitrary endofunctor on a cocomplete category using pairs of natural transformations. This approach is proved to be equivalent to one of equational classes defined by equation arrows. Free algebras in the varieties are investigated and their existence is proved under the assumptions of accessibility. In universal algebra we deal with varieties – classes o...
متن کاملAlmost Free Algebras
In this paper we adopt the terminology of universal algebra. So by a free algebra we will mean that a variety (i.e., an equationally defined class of algebras) is given and the algebra is free in that variety. We will also assume that the language of any variety is countable. In this paper the investigation of the almost free algebras is continued. An algebra is said to be almost free if “most”...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Czechoslovak Mathematical Journal
سال: 1977
ISSN: 0011-4642,1572-9141
DOI: 10.21136/cmj.1977.101461