2015/04/06 by Palle E. T. Jorgensen, Jorgensen, Palle E. T., Erin P. J. Pearse +1 · 1 citation
Mathematics · #05C75 #46E22 #46E22. Secondary: 05C50 #47B25 #FOS: Mathematics #Functional Analysis (math.FA) #Primary: 47B32 #math.FA #msc:05C50 #msc:05C75 #msc:46E22 #msc:46E22. #msc:47B25 #msc:47B32
paper · pdf · doi:10.48550/arxiv.1504.01332
17 pages, 3 figures. arXiv admin note: text overlap with arXiv:1103.5792
arxiv created 2015/07/10 · arxiv updated 2015/07/13
We compare the space of square-summable functions on an infinite graph (denoted ℓ2(G)) with the space of functions of finite energy (denoted HE). There is a notion of inclusion that allows ℓ2(G) to be embedded into HE, but the required inclusion operator is unbounded in most interesting cases. These observations assist in the construction of the Krein extension of the Laplace operator on HE. We investigate the Krein extension and compare it to the Friedrichs extension developed by the authors in a previous paper.