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Published online by Cambridge University Press: 23 September 2005
let $e$ be a subset of the boundary of the open unit disc $d$, and let $a$ be the algebra of bounded holomorphic functions on $d$ that extend continuously to $d \cup e$. it is shown that if $f$ is a bounded harmonic function on $d$ that extends continuously to $d \cup e$ and is not holomorphic, then the uniformly closed algebra $a[f]$ generated by $a$ and $f$ contains $c({\overline{d}})$. this result contains as special cases a result on the disc algebra due to čirka and a result on $h^{\infty}(d)$ due to axler and shields. a stronger form of the result, in which $f$ is allowed to have discontinuities on a small subset of $e$, is also established.