Title of Paper: The weak conjecture on spherical classes Author: Nguy\^{e}n H. V. Hung 1991 Mathematics Subject Classification: Primary 55P47, 55Q45, 55S10, 55T15. Address of Author: Department of Mathematics, Vietnam National University, Hanoi, 334 Nguyen Trai Street, Hanoi, Vietnam E-mail address: nhvhung@vnu.edu.vn Abstract: Let $A$ be the mod 2 Steenrod algebra. We construct a chain-level representation of the dual of Singer's algebraic transfer, $$ Tr_k^*: Tor^A_k(F_2,F_2) \to F_2\otimes_A F_2[x_1,...,x_k], $$ which maps Singer's invariant-theoretic model of the lambda algebra to $F_2[x_1^{\pm},...,x_k^{\pm}]$ and is the inclusion of the Dickson algebra into the polynomial algebra $F_2[x_1,...,x_k]$. Based on this chain-level representation, we study some aspects of the weak conjecture on spherical classes and prove it in some special cases. (Address of Paper: Math. Zeit. 231 (1999), 727-743)