TY  - JOUR
AU  - Fernando Galván, José Francisco
AU  - Ruiz Sancho, Jesús María
AU  - Scheiderer, Claus
PY  - 2004
DO  - 10.1090/S0002-9947-03-03438-X
SN  - 0002-9947
UR  - https://hdl.handle.net/20.500.14352/49910
T2  - Transactions of  the American Mathematical Society
AB  - Let A be an excellent ring. We show that if the real dimension of A is at least three then A has in finite Pythagoras number, and there exists a positive semidefinite element in A which is not a sum of squares in A.
LA  - eng
M2  - 2663
PB  - American Mathematical Society
KW  - Positive semi-definite polynomial
KW  - Excellent ring
KW  - Real spectrum
KW  - Complete local ring
TI  - Sums of squares in real rings
TY  - journal article
VL  - 356
ER  -