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{\bf Tsz Lung Chan, Wai Shun Cheung and Tuen Wai Ng}
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{\bf Graceful Tree Conjecture for Infinite Trees}
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One of the most famous open problems in graph theory is the Graceful
Tree Conjecture, which states that every finite tree has a graceful
labeling. In this paper, we define graceful labelings for countably
infinite graphs, and state and verify a Graceful Tree Conjecture for
countably infinite trees.



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