Your manual actually does not state that anywhere. CTRL+F "cost" no result. CTRL+F heirloom, one result:
It actually says that:
1. List of source items separated by commas.
2. List of target items separated by commas.
3. Price of 1 loompoint (no delimiters) (necessary)Just Ctrl+F is not effective sometimes.
Now if I fill in the cost of heirloom and check the box for "item2item" I hit "start" and the screen just minimizes/disappears.
That is strange. Can you run it in console mode - there should error log in console.
When you say you are using Dijkstra's algorithm, does that mean you are giving weights to trades according to their gold and heirloom point balance, then finding the shortest path ?
Not to trades, but to thier "connections" (edges in graph termins), but in general you are right. Basically connection weight means how much you have to spend to get from one trade to another.
In that case is it possible to put the program into an infinite loop if there's a profitable cycle on the market ?
Not to "infinite" (because for now you have to manually download html file) but very long. In fact, "arguments from file" mode was made specially for this.
Also how do you weight heirloom points versus gold ?
Simple - all turned into gold, according to loompoint price - that is why it is necessary.
Also isn't this making a lot of requests on the cRPG server ?
No, because for now you have to download file manually.