diff --git a/polimani.pl b/polimani.pl
index cb4fea0..2f21b4a 100644
--- a/polimani.pl
+++ b/polimani.pl
@@ -29,6 +29,52 @@
 */
 :- use_module(library(clpfd)).
 
+                 /*******************************
+                 *        USER INTERFACE        *
+                 *******************************/
+
+/*
+    poly2list/2 transforms a list representing a polynomial (second
+    argument) into a polynomial represented as an expression (first argu-
+    ment) and vice-versa.
+*/
+poly2list(P, L) :-
+    polynomial_to_list(P,L).
+
+/*
+    simpolylist/2 simplifies a polynomial represented as a list into
+    another polynomial as a list.
+*/
+simpoly_list(L, S) :-
+    simplify_polynomial_list(L, S).
+
+/*
+    simpoly/2 that simplifies a polynomial represented as an expression
+    as another polynomial as an expression.
+*/
+simpoly(P, S) :-
+    simplify_polynomial(P, S).
+
+/*
+    scalepoly/3 that multiplies one polynomial as expression by a scalar
+    resulting in a second polynomial. The two first arguments are assumed to
+    be ground. The polynomial resulting from the sum is in simplified form.
+*/
+scalepoly(P1, P2, S) :-
+    scale_polynomial(P1, P2, S).
+
+/*
+    addpoly/3 that adds two polynomials as expressions resulting in a
+    third one. The two first arguments are assumed to be ground.
+    The polynomial resulting from the sum is in simplified form.
+*/
+addpoly(P1, P2, S) :-
+    add_polynomial(P1, P2, S).
+
+                 /*******************************
+                 *            BACKEND           *
+                 *******************************/
+
 %% polynomial_variable_list(-List) is det
 %
 %  List of possible polynomial variables