  In [The Delta Conjecture, Trans. Amer. Math. Soc., to appear] Haglund,
Remmel, Wilson introduce a conjecture which gives a combinatorial prediction
for the result of applying a certain operator to an elementary symmetric
function. This operator, defined in terms of its action on the modified
Macdonald basis, has played a role in work of Garsia and Haiman on diagonal
harmonics, the Hilbert scheme, and Macdonald polynomials [A. M. Garsia and M.
Haiman. A remarkable $q,t$-Catalan sequence and $q$-Lagrange inversion, J.
Algebraic Combin. 5 (1996), 191--244], [M. Haiman, Vanishing theorems and
character formulas for the Hilbert scheme of points in the plane, Invent. Math.
149 (2002), 371-407]. The Delta Conjecture involves two parameters $q,t$; in
this article we give the first proof that the Delta Conjecture is true when
$q=0$ or $t=0$.
