diff --git a/polimani.pl b/polimani.pl
index bca9745..3f0be09 100644
--- a/polimani.pl
+++ b/polimani.pl
@@ -1,4 +1,5 @@
 %% -*- mode: prolog-*-
+%% vim: set softtabstop=4 shiftwidth=4 tabstop=4 expandtab:
 %% Follows 'Coding guidelines for Prolog' - Theory and Practice of Logic Programming
 %% https://doi.org/10.1017/S1471068411000391
 
@@ -9,7 +10,7 @@
 %% reversing of a predicate.
 :- use_module(library(clpfd)).
 
-%% polynomial_variable_list(-List:atom) is det
+%% polynomial_variable_list(-List) is det
 %
 %  List of possible polynomial variables
 %
@@ -22,30 +23,23 @@ polynomial_variable_list([x, y, z]).
 polynomial_variable(X) :-
     polynomial_variable_list(V),
     member(X, V).
-%% polynomial_variable(P) :-
-%%     polynomial_variable_list(V),
-%%     member(X, V),
-%%     P = X^N,
-%%     N == 1.
 %% Tests:
 %% ?- polynomial_variable(x).
 %@ true .
-%% ?- polynomial_variable(x^(1)).
+%% ?- polynomial_variable(a).
 %@ false.
 
 %% power(+X:atom) is semidet
 %
 %  Returns true if X is a power term, false otherwise.
-%  Fully reversible.
 %
 power(P^N) :-
-    %% CPL(FD) library predicate to perform integer comparassions in a reversible way
-    %% If 0 > N succeds, fail, otherwise check if X is a valid variable
-    (zcompare((<), 0, N), polynomial_variable(P)); fail.
-    %% if(zcompare((>), 0, N),
-    %%    fail,
-    %%    polynomial_variable(X)
-    %% ).
+(
+    zcompare((<), 0, N), 
+    polynomial_variable(P)
+;
+    fail
+).
 power(X) :-
     polynomial_variable(X).
 %% Tests:
@@ -54,42 +48,14 @@ power(X) :-
 %% ?- power(x^1).
 %@ true .
 %% ?- power(x^3).
-%@ false.
-%@ false.
-%@ false.
-%@ true .
 %@ true .
 %% ?- power(x^(-3)).
-%@ false.
-%@ false.
-%@ true .
-%@ false.
-%@ true .
-%@ false.
+%@ error.
 %% ?- power(X).
 %@ X = x ;
 %@ X = y ;
 %@ X = z.
 
-%% if(+P, -T, -F) is det
-%
-%  A simple implementation of an if predicate.
-%  Returns T if P is true
-%  or F if P otherwise
-%
-%% if(If_1, Then_0, Else_0) :-
-%%     call(If_1, T),
-%%     (  T == true -> call(Then_0)
-%%     ;  T == false -> call(Else_0)
-%%     ;  nonvar(T) -> throw(error(type_error(boolean,T),_))
-%%     ;  /* var(T) */ throw(error(instantiation_error,_))
-%%     ).
-if(P, T, F) :- (P == true, T); F.
-%% ?- if(true, N = 1, N = 2).
-%@ N = 1 .
-%% ?- if(false, N = 1, N = 2).
-%@ N = 2.
-
 %% term(+N:atom) is det
 %
 %  Returns true if N is a term, false otherwise.
@@ -116,17 +82,17 @@ term(L * R) :-
 %  predicate the problem ocurred.
 %
 is_term_valid_in_predicate(T, F) :-
-(
+    (
         term(T)
-;
+    ;
         write("Invalid term in "),
         write(F),
         write(": "),
         write(T),
         fail
-).
+    ).
 %% Tests:
-%% ?- is_term_valid_in_predicate(1, "Foo").
+%% ?- is_term_valid_in_predicate(1, "Chuck Norris").
 %@ true .
 
 %% polynomial(+M:atom) is det
@@ -259,20 +225,24 @@ join_like_terms([], []).
 %% simplify_polynomial(+P:atom, -P2:atom) is det
 %
 %  Simplifies a polynomial.
+%  TODO: not everything is a +, there are -
 %
 simplify_polynomial(M, M2) :-
     %% Are we dealing with a valid term?
-    is_term_valid_in_predicate(M, "simplify_polynomial(M, M2)"),
+    %is_term_valid_in_predicate(M, "simplify_polynomial(M, M2)"),
+    term(M),
     %% If so, simplify it.
     simplify_term(M, M2),
     !.
 simplify_polynomial(P + 0, P) :-
     %% Ensure valid term
-    is_term_valid_in_predicate(P, "simplify_polynomial(P + 0, P)"),
+    %is_term_valid_in_predicate(P, "simplify_polynomial(P + 0, P)"),
+    term(P),
     !.
 simplify_polynomial(0 + P, P) :-
     %% Ensure valid term
-    is_term_valid_in_predicate(P, "simplify_polynomial(0 + P, P)"),
+    %is_term_valid_in_predicate(P, "simplify_polynomial(0 + P, P)"),
+    term(P),
     !.
 simplify_polynomial(P + M, P2 + M2) :-
     simplify_polynomial(P, P2),
@@ -295,7 +265,6 @@ simplify_polynomial(P + M, P2 + M2) :-
 %
 %  Simplifies a list of polynomials
 %
-
 simplify_polynomial_list([L1], L3) :-
     simplify_polynomial(L1, L2),
     L3 = [L2].
@@ -306,6 +275,75 @@ simplify_polynomial_list([L1|L2],L3) :-
     % There is nothing further to compute at this point
     !.
 
+%% polynomial_to_list(+P:polynomial, -L:List)
+%
+%  Converts a polynomial in a list.
+%  TODO: not everything is a +, there are -
+%
+polynomial_to_list(T1 + T2, L) :-
+    polynomial_to_list(T1, L1),
+    L = [T2|L1],
+    % The others computations are semantically meaningless
+    !.
+polynomial_to_list(P, L) :-
+    L = [P].
+%% Tests:
+%%?- polynomial_to_list(2*x^2+5+y*2, S).
+%@S = [y*2, 5, 2*x^2].
+
+%% list_to_polynomial(+P:polynomial, -L:List)
+%
+%  Converts a list in a polynomial.
+%  TODO: not everything is a +, there are -
+%
+list_to_polynomial([T1|T2], P) :-
+    list_to_polynomial(T2, L1),
+    (
+        not(L1 = []),
+        P = L1+T1
+    ;
+        P = T1
+    ),
+    % The others computations are semantically meaningless
+    !.
+list_to_polynomial(T, P) :-
+    P = T.
+%% Tests:
+%% TODO
+
+%% append_two_atoms_with_star(+V1, +V2, -R) is det
+%
+%  Returns R = V1 * V2
+%
+append_two_atoms_with_star(V1, V2, R) :-
+    % Convert term V2 into a string V3
+    term_string(V2, V3),
+    % Concat atom V1 with * into a compound V4
+    atom_concat(V1, *, V4),
+    % Concat atom V4 with V3 into a compound S
+    atom_concat(V4, V3, S),
+    % Convert compound S into a term R
+    term_string(R, S).
+%% Tests:
+%  ?- append_two_atoms_with_star(2, x^2, R).
+%@ R = 2*x^2.
+%@ R = 2*x^2.
+%@ R = 2*3.
+
+%% scale_polynomial(+P:polynomial,+C:constant,-S:polynomial) is det
+%
+%  Scales a polynomial with a constant
+%
+scale_polynomial(P, C, S) :-
+    polynomial_to_list(P, L),
+    maplist(append_two_atoms_with_star(C), L, L2),
+    list_to_polynomial(L2, S).
+%simplify_polynomial(S1, S).
+%% Tests:
+%% ?- scale_polynomial(3*x^2, 2, S).
+%@ S = 2*3*x^2.
+%@ S = 2*(3*x^2).
+
 %% monomial_parts(X, Y, Z)
 %
 %  TODO Maybe remove