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document {
Key => baseRings,
Headline => "store the list of base rings of a ring",
TT "baseRings", " -- a symbol used as a key in a ring ", TT "R", " under which is
stored a list of base rings for ", TT "R", ".",
PARA{
"A base ring ", TT "A", " of ", TT "R", " is one of the rings involved in the
construction of ", TT "R", "."
},
PARA{ "The base rings are presented in chronological order." },
SeeAlso => { baseRing }
}
document {
Key => {baseRing,(baseRing, Ring)},
Headline => "produce the ring from which a ring was formed",
Usage => "baseRing R",
Inputs => { "R" => Ring },
Outputs => { Ring => "the ring from which ", TT "R", " was formed" },
PARA {
"The base ring of a ring ", TT "R", " is the ring from which ", TT "R", " was formed.
For example, if ", TT "R", " is a quotient ring of the form ", TT "S/I", ",
or if ", TT "R", " is a fraction ring of the form ", TT "frac S", ",
or if ", TT "R", " is a polynomial ring over ", TT "S", ",
then the base ring is ", TT "S", "."
},
EXAMPLE lines ///
baseRing QQ
R = QQ[x,y]
S = R / (x^2 + y^3 - 1)
T = frac S
baseRing T
baseRing S
baseRing R
///,
PARA {
"The entire chain of base rings can be obtained under the key ", TO "baseRings", "."
},
EXAMPLE "T.baseRings",
Subnodes => { TO "baseRings" },
}
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