# ApCoCoA-1:NCo.BLW

## NCo.BLW

The leading word of a non-zero polynomial in a free monoid ring over the binary field F_{2}={0,1}.

### Syntax

NCo.BLW(F:LIST):STRING

### Description

*Please note:* The function(s) explained on this page is/are using the *ApCoCoAServer*. You will have to start the ApCoCoAServer in order to use it/them.

Please set ring environment *alphabet* (or set of indeterminates) `X` and *word ordering* via the functions NCo.SetX and NCo.SetOrdering, respectively, before calling this function. The default ordering is the length-lexicographic ordering ("LLEX"). For more information, please check the relevant functions.

@param

*F:*a non-zero polynomial in the free monoid ring`F_{2}<X>`. Each polynomial is represented as a LIST of words (or terms) in`<X>`. Each word is represented as a STRING. For example,`xy^2x`is represented as "xyyx", and the identity is represented as the empty string "". Thus, the polynomial`F=xy-y+1`in`F2<x,y>`is represented as F:=["xy", "y", ""]. The zero polynomial`0`is represented as the empty LIST [].@return: a STRING which represents the leading word of F with respect to the current word ordering. If F=0, the function returns nothing.

#### Example

NCo.SetX(<quotes>xX</quotes>); NCo.SetOrdering(<quotes>LLEX</quotes>); F1:=[<quotes>xX</quotes>,<quotes>Xx</quotes>]; NCo.BLW(F1); xX ------------------------------- NCo.BLW([]); -------------------------------

### See also