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Let |$k_i\ (i=1,2,\ldots ,t)$| be natural numbers with |$k_1>k_2>\cdots >k_t>0$|⁠ , |$k_1\geq 2$| and |$t

We obtain bounds on fractional parts of binary forms of the shape $$\Psi(x,y)=\alpha_k x^k+\alpha_l x^ly^{k-l}+\alpha_{l-1}x^{l-1}y^{k-l+1}+\cdots+\alpha_0 y^k$$ with |$\alpha_k,\alpha_l,\ldots,\alpha_0\in{\mathbb R}$| and |$l\leq k-2.$| By exploiting recent progress on Vinogradov's mean value theorem and earlier work on exponential sums over smooth numbers, we derive estimates superior to those obtained hitherto for the best exponent σ , depending on k and |$l,$| such that $$ \min_{\substack{0\leq x,y\leq X\\(x,y)\neq (0,0)}}\|\Psi(x,y)\|\leq X^{-\sigma+\epsilon}. $$ [ABSTRACT FROM AUTHOR]