& lt= = & gt& lty，x & gt∈R .S

& lt= = & gt& lty，z & gt∈R∧& lt； z.x & gt∈S

& lt= = & gt& ltx，z & gt∈s^(- 1)∧<； z，y & gt∈R^(- 1)

& lt= = & gt& ltx，y & gt∈S^(- 1)。 R^(- 1)

(2) Right? & ltx，y & gt∈(R^(- 1))^(- 1)

& lt= = & gt& lty，x & gt∈R^(- 1)

& lt= = & gt& ltx，y & gt∈R

If you don't understand, please ask. If it helps, please adopt it. Thank you!