We present an algorithm which converts a given Sagbi basis of a polynomial
$K$-subalgebra $\mathcal{A}$ to a Sagbi basis of $\mathcal{A}$ in a polynomial
ring with respect to another term ordering, under the assumption that
subalgebra $\mathcal{A}$ admits a finite Sagbi basis with respect to all term
ordering. The Sagbi walk method converts a Sagbi basis by partitioning the
computations following a path in the Sagbi Fan. The algorithms have been
implemented as a library for the computer algebra system SINGULAR \cite{GPS1}.
The theory of "subalgebra basis" analogous to standard basis (the
generalization of Gr\"{o}bner bases to monomial ordering which are not
necessarily well ordering \cite{GP1}.) for ideals in polynomial rings over a
field is developed. We call these bases "SASBI Basis" for "Subalgebra Analogue
to Standard Basis for Ideals". The case of global orderings, here they are
called "SAGBI Basis" for "Subalgebra Analogue to Gr\"{o}bner Basis for Ideals",
is treated in \cite{RS1}. Sasbi bases may be infinite.
The theory of "subalgebra basis" analogous to standard basis (the
generalization of Gr\"{o}bner bases to monomial ordering which are not
necessarily well ordering \cite{GP1}.) for ideals in polynomial rings over a
field is developed. We call these bases "SASBI Basis" for "Subalgebra Analogue
to Standard Basis for Ideals". The case of global orderings, here they are
called "SAGBI Basis" for "Subalgebra Analogue to Gr\"{o}bner Basis for Ideals",
is treated in \cite{RS1}. Sasbi bases may be infinite.