Universal objects in qasiconstructs
نویسنده
چکیده
The general theory of Jónsson-classes is generalized to strongly smooth quasiconstructs in such a way that it also allows the construction of universal categories. One example of the theory is the existence of a concrete universal category over every base category. Properties are given which are (under certain conditions) equivalent to the existence of homogeneous universal objects. Thereby, we disprove the existence of a homogeneous C -universal category. The notion of homogeneity is strengthened to extremal homogeneity. Extremally homogeneous universal objects, for which additionally every morphism between smaller subobjects is extendable to an endomorphism, are constructed in so called extremally smooth quasiconstructs.
منابع مشابه
k-Abortable Objects: Progress Under High Contention
In this paper, we define k-abortable objects, the first kind of abortable objects [2,7] that guarantee some degree of progress even under high contention. The definition is simple and natural: intuitively, an operation on a k-abortable object can abort only if k operations from distinct processes succeed during the execution of the aborted operation. We first show that k-abortable objects can e...
متن کاملUniversal Constructions for Large Objects
We present lock-free and wait-free universal constructions for implementing large shared objects. Most previous universal constructions require processes to copy the entire object state, which is impractical for large objects. Previous attempts to address this problem require programmers to explicitly fragment large objects into smaller, more manageable pieces, paying particular attention to ho...
متن کاملKohonen Self Organizing for Automatic Identification of Cartographic Objects
Automatic identification and localization of cartographic objects in aerial and satellite images have gained increasing attention in recent years in digital photogrammetry and remote sensing. Although the automatic extraction of man made objects in essence is still an unresolved issue, the man made objects can be extracted from aerial photos and satellite images. Recently, the high-resolution s...
متن کاملThe RedBlue Adaptive Universal Constructions
We present the family of RedBlue algorithms, a collection of universal wait-free constructions for linearizable shared objects in an asynchronous shared-memory distributed system with n processes. The algorithms are adaptive and improve upon previous algorithms in terms of their time and/or space complexity. The first of the algorithms is of theoretical interest only; it achieves better time co...
متن کاملA Thrifty Universal Construction
A universal construction is an algorithm which transforms any sequential implementation of an object into a concurrent implementation of that same object in a linearizable and wait-free manner. Such constructions require underlying low-level universal shared objects such as compare-and-swap and load-linked/store-conditional . In this paper, we present the first universal construction that (a) u...
متن کامل