We give
a complete obstru
ction to turning
an immersion <
a n
ame="mml10">
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a style="text-de
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cien
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athURL&_method=retrieve&_udi=B6V1J-4GGWG74-1&_m
athId=mml10&_user=10&_
cdi=5676&_rdo
c=3&_h
andle=V-WA-A-W-E-MsSAYVW-UUW-U-AABZBUYWWC-AABBYYEUWC-CADDVABAE-E-U&_
acct=C000050221&_version=1&_userid=10&md5=44e7e7053
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c7" title="Cli
ck to view the M
athML sour
ce">
f:
Mm→
Rna> into
an embedding when <
a n
ame="mml11">
a><
a style="text-de
cor
ation:none;
color:bl
ack" href="/s
cien
ce?_ob=M
athURL&_method=retrieve&_udi=B6V1J-4GGWG74-1&_m
athId=mml11&_user=10&_
cdi=5676&_rdo
c=3&_h
andle=V-WA-A-W-E-MsSAYVW-UUW-U-AABZBUYWWC-AABBYYEUWC-CADDVABAE-E-U&_
acct=C000050221&_version=1&_userid=10&md5=9e4020
a593d467d6b
ca46bf0193
cc50b" title="Cli
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athML sour
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n![]()
c="http://www.s
cien
cedire
ct.
com/s
cidirimg/entities/2
a7e.gif"
alt="gre
ater-or-equ
al, sl
anted" border=0>4
m+5
a>. It is
a se
cond
ary obstru
ction,
and exists only when the prim
ary obstru
ction, due to André H
aefliger, v
anishes. The obstru
ction lives in
a twisted
cobordism group,
and its v
anishing implies the existen
ce of
an embedding in the regul
ar homotopy
cl
ass of
f in the r
ange indi
cated. We use Tom Goodwillie's
cal
culus of fun
ctors, following Mi
ch
ael Weiss, to help org
anize
and prove the result.