From stress testing it, I seem to be able to buy 5 shares, and then sell 6, which is of course illegal.
fixed. Also added "risk to win" and decimal odds.
The theme is cracking me up. What century are we in?
The century before bootstrap (twitter's css theme).
I noticed a bug: when I bought some shares (2000 on every event) the "change prob. to" is not working - see screenshot attached.
EDIT: hm, guess the attachment did not work. However - it should be easy to reproduce.
2000 is a huge amount, I mostly experiment with sizes around 10-100. Anyway, that field isn't yet robust, you'll see a lot of NaN's and Infinity's if you change that field directly. It needs the ability to "sell short" an outcome (ie. buy an equal amount on every other outcome) before it can be robust. Until then, entering a probability that's lower than the current one will cause those errors (not sure if its the same bug you saw. I've used imgur to post screenshots here).
And I noticed one more thing: As a event author it will be VERY HARD to get your initial investment back.
The basic LMSR market maker isn't designed to be profitable - its designed to be subsidized. One thing that might alleviate this, even for basic LMSR, is to use an initial "b" vector with the probabilities at Vegas odds. Not sure how much this would help (and it would depend on the outcome anyway), but its on the TODOs (in the repo readme). Right now the b vector is uniform probabilities (ie, starts at 0.25 on all 4 outcomes).
Another of the TODOS is volume-parameterized (aka liquidity-sensitive) LMSR - where the "b" parameter increases as trade volume increases. These designs replace the "b" parameter with an "alpha" parameter, which acts as a percentage fee and creates a profit-making market-maker. Note that traditional sportsbooks maintain a "vig" of around 4%-5%.
I think it would be necessary to place classical buy/sell orders in the truthcoin blockchain that either get active as soon as the market maker price goes below them or that could be matched by other orders directly.
I like the idea of a hybrid classical order book + LMSR, described here
. This would let users make offers, which adds liquidity (opposed to only permitting users to take offers, which in basic LMSR do not add liquidity).