I can't visualize the profit/loss of a position described in terms of its Up-Gamma and Down-Gamma. The question arise from pag. 193 of Dynamic Hedging by Taleb.
How would you describe a position that is long up-gamma and short down-gamma in terms of profit and loss? How the signs of the up-gamma and down-gamma affect the position?
My idea: P/L increases "more than linearly" if the underlying price increase thanks to the positive effect of positive and greater value of up-gamma (long up-gamma). The P/L are affected positively by smaller value of down-Gamma, possibly negative values, that implies a P/L where the losses are "capped".
Edit
My second interpretation is that "short" Down-Gamma only means that the Down-Gamma of the position is negative. If I am right, this is coherent with a risk reversal but not with a diagonal ratio spread, the two examples presented by the author. Or it could be coherent provided that the P/L is concave when the asset price is declaning. Basically, to visualize the P/L more information is required is my opinion.
If I am not clear, please, let me know. Thanks for the help.