#feedback I think there is a flaw in this diagraming.

The stim is not saying that:

All "brick houses(BH)" have "front yards(FY)" and most brick houses with front yards have "Two stories (2S)." That is what you diagrammed with:

BH→FY‑m→2S

What the stim is saying is that on River street: All brick houses (BH) have front yards (FY) ALSO, most Houses with front yards have 2 stories(2S)

We have no idea how many houses are on River Street nor what percentage of them are brick. It is absolutely possible that the street has 100 houses, all 100 of them could have front yards, but only 1 of them is Brick. That means that we can reasonably have a situation where most houses with front yards have 2 stories and NONE of them are brick houses. This is why we cannot infer anything about the number of floors in brick houses from the information provided.

Should it not be:

Domain: River Street

Brick + House → FY

House + FY ‑m→ 2S

(Brick + House) and (House + FY) have no guaranteed overlap and cannot be linked.

Did I misinterpret the stim in some way?

Another good way to look at it is what the answer does.

Sufficient Assumptions are strong answers that make the conclusion stronger. They are there to beef up the logic and make it more likely to be true.

Necessary assumptions on the other hand are not trying to prove or strengthen anything. Necessary assumptions are proved by the information already in the stimulus. They are almost always weaker than SA because their purpose is not to prove the conclusion correct but to be required by the logic of the Existing facts. They are often unassuming almost "Duh, obviously" type answers. Be careful not to fall into the trap of thinking that an NA answer is too weak to be right. It is not supposed to be powerful, but provable.

Ok. So I know that this has been mentioned a few times in this thread, but I want to see if I can articulate the confusion more clearly.

I understand that /(traffic congestion decreases[TCD])→/(Profits of DownTown Business increase [PI])

can be negated to:

PI → TCD

But this is something you can infer from a fact. If Profits increase then we know that traffic had to decrease. But it seems like this should not chain because it is not a causal relationship it is an exception. That means that if we want to have PI then we need to have TDC AND More Consumers Living in the Downtown Area [MC]. If either of these conditions are not met then /PI.

No causal relationship was made between MC and TCD so while it might graph in Lawgic, but logically it is nonsensical. there is no way to draw a line between more people living in Downtown to traffic decreasing given what we know.

MC is enough to prove PI only if TCD is met as well

Should it not be written as

(Decreased cost of Living[DL]) → MC → PI

EXCEPT: /TDC

Shouldn't number 4 [A pet adoption center(PA) with at least ten years of continuous operations (10+) will be supported by the Mittens Foundation(SMF) if it shelters more than fifty animals. (50+) ]

Be diagramed like:

PA and 10+ and 50+ -> SMF

Isn't "if it shelters more than fifty animals" also a sufficient condition?