In the old days a reduce means - recreate ;-)

If you do not care about the data:

#umount your FS mounted on /d3
umount /d3

# remove the FS with the mount point /d3. The rmfs will remove the FS
and the underlying LV
rmfs /d3

# Now a lsvg vold3 should show 545 free PP's . One PP is used normaly
for the JFS log.
lsvg vold3

# Now recreate the filesystem with the size of 1 PP ( We will not care
about the LV names ) or if you know the final size replace the 1 with
the amount of 512BytesBLock
crfs -v jfs -g vold3 -a size=1 -m /d3 -A yes
crfs -v jfs -g vold3 -a size=1 -m /d4 -A yes
mount /d3
mount /d4
# or use 'smitty crfs' .
Afterwards you should be able to increase the FS /d3 /d4 with
chfs -a size=NewSizeIn512BytesBlock /d3
chfs -a size=NewSizeIn512BytesBlock /d4

hth
Hajo