7.2.2.4 map related functions (plural)

fetch (plural)

the identity map between rings and qrings (see fetch (plural))

imap (plural)

a convenient map procedure for inclusions and projections of rings (see imap (plural))

preimage (plural)

preimage under a ring map (see preimage (plural))

subst

substitute a ring variable (see subst (plural))

See also ncpreim_lib for the advanced preimage algorithm.