Help with building my first trigger

Hi there. I want to build a trigger that places a lay bet on an in play horse racing win market. The lay price has a condition that is decided on a formula that involves the win market BSP, the place market BSP and the market commission. If the last traded price is less than the outcome of the formula then place a lay bet at the best back price minus 1 tick at a pre-determined liability (eg $10). Other conditions for the lay bet are market volume pre-off is over $200,000 AUD  (or 100,000 pounds, I'm from Australia), minimum win BSP is a set constant and maximum win BSP is a set constant.

I'm not asking for anyone to build this for me, I would like to do it myself. I have previously used Bet Angel and have built a number of automation so I'm not a completely newbie but I am a bit stuck and would really appreciate a nudge in the right direction.

Hi
OK, here are some pointers:

lay to a fixed liability: liability/(lay_price-1) your example: 10.00/(lay_price-1)

price, best back price minus 1 tick: r_ticks(back_price, -1)

for your win / place cross-market formula search the helpfile for winplace_ prefix. you can construct expressions in one market based on values in the other market

volume condition: markets matched volume is greater than 200000

great to see you wanting to learn  

Thanks MarkV, your reply has helped me out a lot. I have one more question: is the variable "commission" a whole number or a decimal,  IE if the commission is 5% does it hold the value 5 or 0.05?

Hi
It's decimal and the value will be the commission rate according to your Betfair account.

Tip: use the View Variables Window to see the value of any variables or formulas live.  

Thank you once again, I appreciate your help.