I agree with Robusto, I think. There is a semantic difference between "allow" and "allow for". "B did X, allowing Y" implies that by doing X, B directly caused Y to happen. However, "B did X, allowing for Y" implies that doing X may or may not, in fact, actually cause Y; Y may happen with or without X, or Y may require something else to happen besides or in addition to X.
Short non-sequitur, but consider a sentence in the context of carpentry. "He spaced the boards a quarter-inch from the wall, allowing expansion". Those who know carpentry know that you don't "allow" boards to expand; they simply swell and shrink with temperature and humidity regardless of what you do. Instead, you must "allow for" the boards to expand by taking an action ensuring that WHEN they expand, there is no adverse consequence. So, the correct statement, in context, is "He spaced the boards a quarter-inch from the wall, allowing for expansion".
Back to your OP, "a ceasefire allowing talks" implies that talks will not happen without a ceasefire happening first. "A ceasefire allowing for talks" may imply that talks are already happening, or that they could happen regardless of a ceasefire, but that the ceasefire facilitates those talks. Either may be correct, depending on the situation being described.
So, "allow" denotes permission, and thus a direct cause/effect. "Allow for" denotes either facilitation or "proaction" in anticipation of, and thus breaks the direct cause/effect relationship.
Best Answer
To "decide on something" means to make a decision in relation to a situation, whereas to "decide for something" means to make a decision in favour of a party in a dispute.
For example, if group A wants to build a monument and group B wants to have a bank holiday, then you could 'decide for group A' (referring directly to the dispute) or you could 'decide on building a monument' (not referring directly to the dispute).
Also:
decide on vs. decide against
(in disputes) decide for vs. decide against