TASK DEFINITION: Generate the answer for a given question. The question requires common knowledge of English. Make sure that the answer is in detail, long, consistent with the context, and requires general knowledge of English. To be less repetitive, please vary your language for each question. Give a proper explanation to answer, and if necessary, provide the definition of various terms. And conclude your answer if it's long. If you have used other resources (e.g., Merriam Webster's.) to answer the question, include citations in your answer. You don't need to paraphrase the context of your resources, but make sure that your answer is consistent and complete.
PROBLEM: I've read this and this. I know that the underlying question has been answered, my problem is of a different nature: I'm currently writing my master's thesis in CS and my professor thinks that the apostrophe possessive is only applicable to people. He claims to have spoken to a linguist from Cambridge who confirmed his opinion. Neither my professor nor I am a native speaker and the thesis is being written in Germany. Now, I know that he won't care if I just send him a couple of links to the answers here. So my question is: How do I convince my professor? Are there any 'more scientific™' sources that I can point to? Examples of phrases: If each plant's humidity is displayed publicly [...] [...] shows an overview of the node's structure. Due to an issue in the network stack's IPv6 subsystem [...].

SOLUTION: As few people are addressing the ''more scientific™' sources' bit of the question, it should be pointed out that there are a number of English style guides out there, practically all of which should cover the topic of forming possessives with apostrophe-s (as it's a frequent issue even with native speakers). You should be able to find copies of at least one of the major ones in any decent University library. (At least at any decent University with English classes.) The Elements of Style by Strunk and White is the 'gold standard' for many Americans, although there are many who disagree with many of the details. The Chicago Manual of Style is a well-used standard for (American) University usage. - The online version is unapologetic and direct on this topic: 'The possessive of most singular nouns is formed by adding an apostrophe and an s', although it does go into more details. Fowler's modern English usage by Henry Fowler is also a well-regarded standard, particularly for British users. The Cambridge Guide to English Usage by Pam Peters has the benefit of the 'authority' of Cambridge. Oxford, of course, has their own: The New Oxford Style Manual, though the title has varied with edition. If physical copies aren't something you're interested in, a number of organizations (particularly journalism houses) have their house style guides online. For example, the Economist makes no mention of the conjectured rule in its advice. The Guardian gives additional examples, and also completely omits the purported rule. Others can likely be found by searching, and other major organizations (like the Associate Press and the New York Times) have theirs as printed books. Many dictionaries also have usage notes in them. (In particular, I'll point out the comment from @ps2goat mentioning Oxford Dictionaries's online page.) Ultimately, though, it's exceedingly difficult to prove a negative. Even confronted with evidence that a large number of style guides and usage manuals for English have nothing approaching the purported rule, your professor might not be convinced that he is mistaken. If that is the case, your best choice is probably to reword things to avoid the issue.

PROBLEM: In computer programming, when you append a 'string' to another, you add it to the end of the former string. E.g. String string1 = 'abcd'; String string2 = 'efgh'; Appending the two strings would give 'abcdefgh' But what if I wanted to add string2 before string1 to have the result: 'efghabcd' What would be a good name for that that reverse operation? What is the opposite of 'append'?.

SOLUTION: Prepend: (computing, linguistics, transitive) To attach (an expression, phrase, etc.) to another, as a prefix.

PROBLEM: What is the plural of syntax? Would it be syntacies? What rule would govern this kind of construction?.

SOLUTION:
As FumbleFingers has commented, the plural is syntaxes. That's probably because the normal plural -es is added to the root word, or it may possibly be because the Greek/Late Latin word from which syntax is derived is syntaxis and Greek words ending in -is are pluralised with -es. If we were to create a spoof plural for syntax it would be syntaces (words ending -x get -ces; the preceding vowel can change as in index/indices). But no-one uses that, or would know what it meant.