and
if you feed one but not the other, that is permitted

ppauper wrote:

and
if you feed one but not the other, that is permitted

Indeed; a judge would not sentence you.a good one, that is.

Should I use a comma in the below sentence?
"Factor X reduces the value of a and b [to commar or not to commar] while increasing the value of c."

No, it reads better straight through with no pause.

P.S. "While" is a time-related word implying factor X is affecting a dynamic system over time. If Factor X is a logical condition (e.g., the first letter of a person's name) rather than a temporal property, then "whereas it increases the value of c" might be more correct. And if this a correlation (not a proven cause) then that affects the wording, too. Also is it "factor X" or high values of factor X that are associated with or cause conditional differences or dynamic changes in the other variables?

Traden4Alpha wrote:

]
P.S.  "While" is a time-related word implying factor X is affecting a dynamic system over time.

this statement is inaccurate because "while" as a conjunction has more than one meaning.

conjunction: while
1. during the time that; at the same time as.
"nothing much changed while he was away"
2. whereas (indicating a contrast).
"one person wants out, while the other wants the relationship to continue"

"while" is the correct word to use here.

However, a stickler for grammar might take exception to the use of a "dangling participle."
Thinking back many years to my PhD defense, I remember being savaged by one of the examiners (who was a very senior person in my field) for having several dangling participles in my dissertation, and I suspect he would rather wrote "while it increases"

katastrofa wrote:

Should I use a comma in the below sentence?
"Factor X reduces the value of a and b [to commar or not to commar] while increasing the value of c."

Comma won't help; it does not remove the ambiguity. ppauper is correct.
A good test is: how would a programmer implement this text in C?

ppauper wrote:

Traden4Alpha wrote:

]
P.S.  "While" is a time-related word implying factor X is affecting a dynamic system over time.  

this statement is inaccurate because "while" as a conjunction has more than one meaning.

conjunction: while
1. during the time that; at the same time as.
"nothing much changed while he was away"
2. whereas (indicating a contrast).
"one person wants out, while the other wants the relationship to continue"

"while" is the correct word to use here.

However, a stickler for grammar might take exception to the use of a "dangling participle."
Thinking back many years to my PhD defense, I remember being savaged by one of the examiners (who was a very senior person in my field) for having several dangling participles in my dissertation, and I suspect he would rather wrote "while it increases"

I think I've been attacked on similar grounds (but I'm distrustful since the attacker yields some terrible errors themselves, e.g. "differ" -> "differentiate" or "alternative" -> "alternate" - aargh!). I am aware of the shortcomings and foregoings of my English grammar, but I cannot see how the participle construction in my sentence contains any ambiguity - actually, the whole subordinate clause with a repeated subject seems to me less efficient and slightly confusing. Is this purism or rather some snobbery? Similarly, the passive voice - in some scientific journals it's practically illegal to use it - ?!
Thanks guys. Definitely no comma and I will sleep on the above for a while.

Is this for an article? 
A good trick is to break the sentence into two uncoupled sentences and use active voice.

 I don't know what X,a,b and c are but I would define them like in maths books and then draw conclusions in such a way that no lawyer can whinge about them

"Factor X reduces the value of a and b [to commar or not to commar] while increasing the value of c."

??
Factor X is a monotonic decreasing as a function of a and b while it is monotonic increasing in c.

Maybe make the English as close to maths as possible. Sumphing like that.

Perhaps,

Factor X reduces the value of a and b and increases the value of c.

or

Factor X reduces the value of a and b but increases the value of c.

ppauper wrote:

Perhaps,

Factor X reduces the value of a and b and increases the value of c.

or

Factor X reduces the value of a and b but increases the value of c.

I like the first one unless reader must watch out ACHTUNG for the case of to warn the reader. I don't know the context.
Factor X reduces the value of a and b; however, it increases the value of c.

however is good

I really like ppauper's "Factor X reduces the value of a and b but increases the value of c."
Thank you! You are my little angels <3

from an old, old thread started by professor hamilton, "Help Terri by eating lots of food on Easter," cuch has suggested it should be "at Easter" rather than "on Easter"

Cuchulainn wrote:

'at' Easter

I suspect that both are correct, depending upon whether you are using Easter to mean Easter Day, which is a perfectly acceptable usage, or using Easter to mean the Easter season. You would say "on Easter Day" not "at Easter Day".