Differential invariants of nonlinear equ
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N.H Ibragimov; M Torrisi; A Valenti
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Article
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2004
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Elsevier Science
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English
⚖ 213 KB
We assumed in Theorem 2 that l 1 6 ¼ 0, where l 1 is the expression defined by Eq. ( 77). If l 1 ¼ 0, the corresponding Eq. ( 8) should be considered separately. Furthermore, the cases l 2 ¼ 0 and l 3 ¼ 0 (see Eqs. ( 78) and ( 79)) are also exceptional because of the following lemma: q