box% sage
┌────────────────────────────────────────────────────────────────────┐
│ SageMath version 9.2, Release Date: 2020-10-24                     │
│ Using Python 3.8.6. Type "help()" for help.                        │
└────────────────────────────────────────────────────────────────────┘
sage: R.<x0,x1,x2,s1,s2,s3> = PolynomialRing(QQ, order='lex')
sage: ideal(-s1+x0+x1+x2, -s2+x0*x1+x0*x2+x1*x2, -s3+x0*x1*x2).groebner_basis()
[x0 + x1 + x2 - s1, x1^2 + x1*x2 - x1*s1 + x2^2 - x2*s1 + s2, x2^3 - x2^2*s1 + x2*s2 - s3]
sage: