On numerical semigroups with at most 12 left elements

For a numerical semigroup S $\subseteq$ N with embedding dimension e, conductor c and left part L = $\cap$ [0, -- 1], set W (S) e|L| c. In 1978 Wilf asked, in equivalent terms, whether $\ge$ 0 always holds, question known since as Wilf's conjecture. Using closely related lower bound $\le$ (S), we show that if |L| 12 then 0, thereby settling conjecture this case. This is best possible, cases are where 13 --1. remains open for 13.