On Two Conjectures About Set-graceful Graphs
β Scribed by Mollard, M.; Payan, C.
- Book ID
- 122414814
- Publisher
- Elsevier Science
- Year
- 1989
- Tongue
- English
- Weight
- 211 KB
- Volume
- 10
- Category
- Article
- ISSN
- 0195-6698
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π SIMILAR VOLUMES
We give graceful numberings to the following graphs: (a) the union of n K4 having one edge in common, in other words the join of K2 and the union of n disjoint K2 and (b) the union of n C4 having one edge in common, in other words the product of K2 and K,,", with n + l not a multiple of 4.
A positive integer m is said to be a practical number if every integer n, with 1 n \_(m), is a sum of distinct positive divisors of m. In this note we prove two conjectures of Margenstern: (i) every even positive integer is a sum of two practical numbers; (ii) there exist infinitely many practical