Relationship between n git branches

I would use:

gitk A C D

... there are probably other git GUIs that produce a prettier rendering of the commit graph, but I've always found gitk fine for this purpose. All the branches and tags are labelled in the "London Underground"-style representation:

_{(source: mark at mythic-beasts.com)}

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You can also use the --simplify-by-decoration option to gitk, since it understands all of the parameters that git rev-list does, for example:

gitk --simplify-by-decoration A C D

You can give this a try:

git log --graph --all --decorate --simplify-by-decoration

It will only show commits that are branch heads or tagged.