Best, Pierre ]]>

For your last sentence (“In an arbitrary Riemannian manifold…”), I assume that you mean the following: the boat dashes in the vertical direction (i.e. as a vector field, X is vertical in the bundle TM), while we want to measure the rate of rotation in any horizontal 2-plane. Thus, we need the connection to specify the choice of horizontal directions. Am I correct? ]]>

Thank you! ]]>

“These three structures are said to be compatible if they satisfy”

— for “r” read “w” ? WFL ]]>

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— for “r” read “w” ? WFL

]]>In fact, maybe n needs to be at least 4 to get to examples which are not known to be Andrews-Curtis trivial (but I am probably out of date on the state of the art).

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