کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4648885 | 1342434 | 2010 | 12 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
The complexity of locally injective homomorphisms
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
ریاضیات
ریاضیات گسسته و ترکیبات
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: The complexity of locally injective homomorphisms The complexity of locally injective homomorphisms](/preview/png/4648885.png)
چکیده انگلیسی
A homomorphism f:G→Hf:G→H, from a digraph GG to a digraph HH, is locally injective if the restriction of ff to N−(v)N−(v) is an injective mapping, for each v∈V(G)v∈V(G). The problem of deciding whether such an ff exists is known as the injective HH-colouring problem (INJ-HOMH). In this paper, we classify the problem INJ-HOMH as being either a problem in P or a problem that is NP-complete. This is done in the case where HH is a reflexive digraph (i.e. HH has a loop at every vertex) and in the case where HH is an irreflexive tournament. A full classification in the irreflexive case seems hard, and we provide some evidence as to why this may be the case.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Discrete Mathematics - Volume 310, Issue 20, 28 October 2010, Pages 2685–2696
Journal: Discrete Mathematics - Volume 310, Issue 20, 28 October 2010, Pages 2685–2696
نویسندگان
Gary MacGillivray, Jacobus Swarts,