Mathematical Sciences Department, IBM TJ Watson Research Center, Yorktown Heights, NY 10598, USA. aclozano@us.ibm.com|Mathematical Sciences Department, IBM TJ Watson Research Center, Yorktown Heights, NY 10598, USA. aclozano@us.ibm.com|Mathematical Sciences Department, IBM TJ Watson Research Center, Yorktown Heights, NY 10598, USA. aclozano@us.ibm.com|Mathematical Sciences Department, IBM TJ Watson Research Center, Yorktown Heights, NY 10598, USA. aclozano@us.ibm.com