An assertion concerning functionally complete algebras and NP-completeness
نویسندگان
چکیده
منابع مشابه
An assertion concerning functionally complete algebras and NP-completeness
In a paper published in J. ACM in 1990, Tobias Nipkow asserted that the problemof deciding whether or not an equation over a nontrivial functionally complete algebra has a solution is NP-complete. However, close examination of the reduction used shows that only a weaker theorem follows from his proof, namely that deciding whether or not a system of equations has a solution is NP-complete over s...
متن کاملContractibility and NP-completeness
For a fixed graph H, let H-CON denote the problem of determining whether a given graph is contractible to H. The complexity of H-CON is studied for H belonging to certain classes of graphs, together covering all connected graphs of order at most 4. In particular, H-CON is NP-complete if H is a connected triangle-free graph other than a star. For each connected graph H of order a t most 4 other ...
متن کاملBroadcasting and NP - completeness
In this note, we answer two questions arising in broadcasting problems in networks. We rst describe a new family of minimum broadcast graphs. Then we give a proof due to Alon of the NP-completeness of nding disjoint spanning trees of minimum depth, rooted at a given vertex.
متن کاملNP-Completeness and Disjoint NP-Pairs
We study the question of whether the class DisjNP of disjoint pairs (A,B) of NPsets contains a complete pair. The question relates to the question of whether optimal proof systems exist, and we relate it to the previously studied question of whether there exists a disjoint pair of NP-sets that is NP-hard. We show under reasonable hypotheses that nonsymmetric disjoint NP-pairs exist, which provi...
متن کاملTuring Machines , P , NP and NP - completeness
I assume that most students have encountered Turing machines before. (Students who have not may want to look at Sipser’s book [3].) A Turing machine is defined by an integer k ≥ 1, a finite set of states Q, an alphabet Γ, and a transition function δ : Q×Γk → Q×Γk−1×{L, S,R}k where: • k is the number of (infinite, one-dimensional) tapes used by the machine. In the general case we have k ≥ 3 and ...
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: Theoretical Computer Science
سال: 2008
ISSN: 0304-3975
DOI: 10.1016/j.tcs.2008.08.028