The standard Polyak–Łojasiewicz condition is attributed to Polyak’s early work; one source says Polyak proposed it in 1963 and that it is a special case of the Łojasiewicz inequality .
Another source states that the PL condition was introduced in Polyak’s early works .
A 2022 paper also refers to the Polyak–Łojasiewicz condition as “[Polyak, 1963]” .
The provided snippets for the PL literature discuss the ordinary Polyak–Łojasiewicz condition, but they do not mention the notation (PL^\circ) .
The provided snippets do not identify a paper that introduced (PL^\circ) specifically .
Therefore, I cannot reliably say that (PL^\circ) was introduced in the “Select-then-differentiate” paper or in any earlier paper based on the available sources.
The standard Polyak–Łojasiewicz condition is attributed to Polyak’s early work; one source says Polyak proposed it in 1963 and that it is a special case of the Łojasiewicz inequality .
Another source states that the PL condition was introduced in Polyak’s early works .
A 2022 paper also refers to the Polyak–Łojasiewicz condition as “[Polyak, 1963]” .
The provided snippets for the PL literature discuss the ordinary Polyak–Łojasiewicz condition, but they do not mention the notation (PL^\circ) .
The provided snippets do not identify a paper that introduced (PL^\circ) specifically .
Therefore, I cannot reliably say that (PL^\circ) was introduced in the “Select-then-differentiate” paper or in any earlier paper based on the available sources.