additional poll type: a fixed number of options will be selected

[mensch72]

In addition to the existing poll types ("one option wins", "options get shares"), add a third type "k options will be selected" where k is any integer >1.

The tally process makes sure no option gets a share of more than 1/k by using an appropriate share overflow algorithm from options higher up in the ranking to options further down. The probability of inclusion of an option is then k times the share of the option. The actual selection is then made by using the "ring around a pie" method.

To enable the overflow algorithm, every participant's "weight" equals the number of positively wapped option divided by k, but at most one, and the conversion from proxy to effective wap makes sure that if less than k options are wapped positively, they are all approved. A participant's share is then proportional to her weight. This makes sure that overflowing shares will always got to approved options.

The poll page then shows inclusion probabilities (e.g. as dark portions of a light square) instead of the pie pieces representing the shares. The text in the expanded option view and the explanation page then explain about this and about any overflows of shares. A slider is colored green if at least part of the participant's share goes to that option.