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--- status: Draft
--- author(s): Gregory G. Smith
--- notes:
document {
Key => {isUnit, (isUnit, ZZ), (isUnit, RingElement), (isUnit, Number)},
Headline => "whether a ring element is a unit",
Usage => "isUnit r",
Inputs => {
"r" => RingElement
},
Outputs => {
Boolean => {TO "true", " if the ", TO2("RingElement","ring element"), " ", TT "r",
" generates an ideal containing the multiplicative identity ", TT "1", " and ",
TT "false", " otherwise" }
},
EXAMPLE {
"R = QQ[z]/(z^2+1);",
"isUnit z",
"S = QQ[x,y]/(1-(x-1)*(y-1));",
"isUnit (x^2 - 2*x + 1)",
"isUnit x"
},
}
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