Function: comp2pui (<n>, <L>) implements passing from the complete symmetric functions given in the list <L> to the elementary symmetric functions from 0 to <n>. If the list <L> contains fewer than <n+1> elements, it will be completed with formal values of the type <h1>, <h2>, etc. If the first element of the list <L> exists, it specifies the size of the alphabet, otherwise the size is set to <n>.
(%i1) comp2pui (3, [4, g]); 2 2 (%o1) [4, g, 2 h2 - g , 3 h3 - g h2 + g (g - 2 h2)]
(%o1) true (%i2)