  We have conducted a high-resolution ``3D'' imaging survey of the CO(1--0),
HCN(1--0), and HCO$^+$(1--0) lines toward the central a few kpc regions of the
Seyfert and starburst galaxies in the local universe using the Nobeyama
Millimeter Array. We detected luminous HCN(1--0) emissions toward a
considerable fraction of these Seyfert galaxies (10 of 12 in our sub-sample),
which indicated that some of these Seyfert galaxies, such as NGC 3079, NGC
3227, NGC 4051, NGC 6764, and NGC 7479, are indeed accompanied with compact
nuclear starburst, given the tight correlation between the HCN(1--0) luminosity
and the star formation rate among star-forming galaxies. However, we suggest
that the elevated HCN(1--0) emission from some of these Seyfert galaxies,
including NGC 1068, NGC 1097, NGC 5033, and NGC 5194, does not signify the
presence of massive starbursts there. This is because these Seyfert nuclei show
abnormally high HCN(1--0)/HCO$^+$(1--0) ratios (2--3), which were never
observed in the starburst nuclei in our sample. This could be attributed to the
overabundance of HCN molecules in the X-ray dominated regions (XDRs) at the
centers of these Seyfert galaxies.
