We present the results of numerical simulations which show the formation of blue compact dwarf ( BCD ) galaxies from merging between very gas-rich dwarfs with extended HI gas disks .
We show that dwarf-dwarf merging can trigger central starbursts and form massive compact cores dominated by young stellar populations .
We also show that the pre-existing old stellar components in merger precursor dwarfs can become diffuse low surface brightness components after merging .
The compact cores dominated by younger stellar populations and embedded in more diffusely distributed older ones can be morphologically classified as BCDs .
Since new stars can be formed from gas transferred from the outer part of the extended gas disks of merger precursors , new stars can be very metal-poor ( { [ Fe / H ] } < -1 ) .
Owing to very high gaseous pressure exceeding 10 ^ { 5 } k _ { B } ( where k _ { B } is the Boltzmann constant ) during merging , compact star clusters can be formed in forming BCDs .
The BCDs formed from merging can still have extended HI gas disks surrounding their blue compact cores .
We discuss whether tidal interaction of gas-rich dwarfs without merging can also form BCDs .