UPDATE: Deleting the Cache using  rm -rf `biber --cache`  solved my problem. I'm a new user of LaTeX and use it the first time to write a thesis. Up until now I had everything running fine and was polishing my text as my citations didn't process anymore. I use Biblatex and Biber and export my literature automatically from Zotero. This is a example: \documentclass[a4paper,11pt,headsepline]{scrartcl}  \usepackage{fontspec} \setsansfont{Arial} \renewcommand\familydefault{\sfdefault} \usepackage[ngerman]{babel} \usepackage[right]{eurosym} \usepackage{geometry} \geometry{left=3cm, right=4cm, top=3cm, bottom=3cm}  \usepackage[backend=biber, style=apa]{biblatex} \addbibresource{Literatur.bib}  \begin{document}  This is some Text.  And a really important citation \parencite{neugebauer2020}.  The \textcite{rkimeasles2020} has some totally important findings.  \end{document}  With these in the .bib file:  @article{neugebauer2020,   title = {Beurteilung des neuen Masernschutzgesetzes in Deutschland: Ergebnisse einer deutschlandweiten Befragung},   shorttitle = {Beurteilung des neuen Masernschutzgesetzes in Deutschland},   author = {Neugebauer, Michael and Ebert, Matthias and Vogelmann, Roger},   date = {2020-11-25},   journaltitle = {Zeitschrift für Evidenz, Fortbildung und Qualität im Gesundheitswesen},   volume = {158-159},   pages = {74--80},   issn = {18659217},   doi = {10.1016/j.zefq.2020.10.009},   url = {https://zefq-journal.com/article/S1865-9217(20)30171-9/abstract},   urldate = {2021-01-27} }  @misc{rkimeasles2020,   title = {{{RKI}}-Ratgeber - {{Masern}}},   editor = {{Robert Koch-Institut}},   date = {2020},   url = {https://www.rki.de/DE/Content/Infekt/EpidBull/Merkblaetter/Ratgeber_Masern.html},   urldate = {2021-01-04},   file = {/Users/dennis/Zotero/storage/AJTINZFI/Ratgeber_Masern.html} }   Running this using Texmaker (Xelatex -&gt; biber -&gt; Xelatex outputs this:  Process started Unicode::UCD: failed to find unicore/version in /var/folders/sn/mrxx700x6wjbb_wbvjt1_x480000gn/T/par-64656e6e6973/cache-2f8a664c3c933a44d096bcc8d018a5e92bced897/inc/lib /var/folders/sn mrxx700x6wjbb_wbvjt1_x480000gn/T/par-64656e6e6973/cache-2f8a664c3c933a44d096bcc8d018a5e92bced897/inc CODE(0x7f871ef8cad8) CODE(0x7f871ef8d0c0) at /var/folders/sn mrxx700x6wjbb_wbvjt1_x480000gn/T/par-64656e6e6973/cache-2f8a664c3c933a44d096bcc8d018a5e92bced897/inc/lib/Biber/Internals.pm line 1238. INFO - This is Biber 2.14 INFO - Logfile is 'Testtex.blg' INFO - Reading 'Testtex.bcf' INFO - Found 2 citekeys in bib section 0 INFO - Processing section 0 INFO - Globbing data source 'Literatur.bib' INFO - Globbed data source 'Literatur.bib' to Literatur.bib INFO - Looking for bibtex format file 'Literatur.bib' for section 0 INFO - LaTeX decoding ... INFO - Found BibTeX data source 'Literatur.bib' WARN - Entry 'neugebauer2020' (Literatur.bib): Invalid format '2020-11-25' of date field 'date' - ignoring WARN - Entry 'neugebauer2020' (Literatur.bib): Invalid format '2021-01-27' of date field 'urldate' - ignoring WARN - Entry 'rkimeasles2020' (Literatur.bib): Invalid format '2020' of date field 'date' - ignoring WARN - Entry 'rkimeasles2020' (Literatur.bib): Invalid format '2021-01-04' of date field 'urldate' - ignoring Process exited with error(s)  Running with Latexmk or Biber directly gives me the same Warnings about the invalid date format.  Biber warning: [217] Utils.pm:304&gt; WARN - Entry 'neugebauer2020' (Literatur.bib): Invalid format '2020-11-25' of date field 'date' - ignoring  I'm at a loss here. From my point of view the date format is correct. I also tried deleting the Biber Cache. No Change. Any ideas?
I'm having exactly the same issue as , also using Biber 2.14, albeit I didn't upgrade, downgrade, change TexLive version, change encoding or (seemingly) do anything. It's like Biber suddenly quit parsing dates on me.  Whether the bibfile is encoded in ASCII or UTF-8 makes no difference. Whether the date is a short format or the full YYYY-MM-DD makes no difference. I'm not sure what else to test.  Here's a MWE and the associated .blg file:  \begin{filecontents}{mwe.bib}     @Article{JD2020,         author       = {John Doe},         title        = {A Title},         date         = {2020-01-01},         %date       = {2020}         journaltitle = {Journal},     } \end{filecontents}  \documentclass{article} \usepackage{biblatex} \addbibresource{mwe.bib}  \begin{document}     test\autocite{JD2020}     \printbibliography \end{document}   [1] Config.pm:304&gt; INFO - This is Biber 2.14 [1] Config.pm:307&gt; INFO - Logfile is 'mwe.blg' [154] biber-darwin:322&gt; INFO - === Thu Apr 30, 2020, 11:04:33 [185] Biber.pm:415&gt; INFO - Reading 'mwe.bcf' [354] Biber.pm:943&gt; INFO - Found 1 citekeys in bib section 0 [384] Biber.pm:4256&gt; INFO - Processing section 0 [385] Utils.pm:75&gt; INFO - Globbing data source 'mwe.bib' [385] Utils.pm:91&gt; INFO - Globbed data source 'mwe.bib' to mwe.bib [401] Biber.pm:4455&gt; INFO - Looking for bibtex format file 'mwe.bib' for section 0 [402] bibtex.pm:1653&gt; INFO - LaTeX decoding ... [406] bibtex.pm:1471&gt; INFO - Found BibTeX data source 'mwe.bib' [437] Utils.pm:304&gt; WARN - Entry 'JD2020' (mwe.bib): Invalid format '2020-01-01' of date field 'date' - ignoring [457] UCollate.pm:68&gt; INFO - Overriding locale 'en-US' defaults 'normalization = NFD' with 'normalization = prenormalized' [457] UCollate.pm:68&gt; INFO - Overriding locale 'en-US' defaults 'variable = shifted' with 'variable = non-ignorable' [457] Biber.pm:4084&gt; INFO - Sorting list 'nty/global//global/global' of type 'entry' with template 'nty' and locale 'en-US' [457] Biber.pm:4090&gt; INFO - No sort tailoring available for locale 'en-US' [461] bbl.pm:652&gt; INFO - Writing 'mwe.bbl' with encoding 'UTF-8' [463] bbl.pm:755&gt; INFO - Output to mwe.bbl [463] Biber.pm:128&gt; INFO - WARNINGS: 1   The \printbibliography output actually looks like this: [1] John Doe. “A Title”. In: Journal ().  In my actual thesis, all the dates are gone from the pdf output.
$(U\cap W)^0 = U^0 + W^0$ Let $V$ be a finite dimensional vector space and $U^0$ and $W^0$ denote the annihilators of subspaces $U$ and $W$, respectively.  Then I need to show that $(U\cap W)^0 = U^0 + W^0$.  I can show that $U^0 + W^0 \subseteq (U\cap W)^0$ like so: Let $f\in U^0$ and $g\in W^0$.  Then, because $U^0, W^0 \subseteq (U\cap W)^0$, we see that if $f\in U^0$ and $g\in W^0$, then for any $v\in U\cap W$ and $a,b \in \Bbb F$, $(af+bg)(v) = af(v) + bg(v) = 0$.  Thus $af+bg\in (U\cap W)^0$.  But because $f$ and $g$ were arbitrary, this implies that any linear combination of elements of $U^0$ and $W^0$ is an element of $(U\cap W)^0$.  I.e. $U^0+W^0 \subseteq (U\cap W)^0$.  But I haven't had any luck proving the other direction.  Obviously I should start with $f\in (U\cap W)^0$.  But then it looks like I need to somehow break that function into two to show its in $U^0 + W^0$.  That's throwing me off. Can I get tourist visa on arrival at Dubai airport? What units does the rotation argument expect when creating objects? I want to create a lamp in blender using python. I want to give the lamp some rotation. As per the  I can set the initial rotation using a tuple of numbers in the function call like this rotation=(0.0, 0.0, 0.0) this is the specifc documentation for the rotation parameter:  rotation: (float array of 3 items in [-inf, inf], (optional)) – Rotation, Rotation for the newly added object  What units is this parameter specified with? It does not seem to be in degrees or radian.  When I try with my example code here where I use rotation=(0, 1, 0) to get 1 degree on the y axis. I end up getting 57.296 degrees after running the code.  import bpy  bpy.ops.object.lamp_add(type='AREA', view_align=False, location=(0, 0, 0), rotation=(0, 1, 0), layers=(True, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False)) In  they've somehow created "wireless" networks, meaning networks that connect two components but don't have an actual wire in the schematics.  What are these called, and how can I create them in Eagle Cad 6.5? I read it in Reader's Digest in the seventies. Archaeologists interpreted everyday objects as the TV set and the toilet seat to be sacred and precious. Discrete and compact subset must be finite I'm trying to show that the group $U(Z_{54})$ is cyclic.  To start, I found the divisors of 54 = {1, 2, 3, 6, 9, 18, 27, 54}  Then I started to find the elements using the powers of a.  Where $U(Z_{54})= &lt;a&gt;$  Therefore, $&lt;a^{54/1}&gt;$={ e }  $ &lt;a^{54/2}&gt;$= { e, $ a^{36}$ }  and such, where the last would be &lt; $a^{54/54}$> = { e }  The things I would like to know is, how does this process show that it's cyclic? Is it because the first divisor (1) and the last divisor (54) is equal to e? Therefore creating a cycle?  Also, what would the &lt; a > to the powers finding the elements process be called?  Thank you! I currently have the Geometry Dash lite version and I want to buy the full version. Can I login with my account of Geometry Dash lite and keep everything I already had? It would suck if I had to redo everything. How can I know what speed card to get for my camera? Cameras rarely specify exactly what speed cards you should be using in them - I just checked the manual for my DSLR, and all it says is to use an SDHD card, and a "high speed" card should be used for recording video.  On the other hand, there are a number of different rating systems for memory card speed (33x! 150x! Class 2! Class 10!) and price seems to increase with speed.  Is there any way to test the maximum write speed the camera is capable of?  Are the read/write speeds documented anywhere? Emmy Noether's theorem in simpler terms I'd like to understand  and its contents as to what it implies in a bit simpler terms. I am familiar with mathematics unto Calculus 1,2,3 and some linear algebra and group theory. I am familiar with that for each symmetry there is a conservation law.    Now is there a one-one correspondence between these two always? What about laws like conservation of charge?  And conservation of energy?  And conservation of mass?  Considering our view of nature was changed as Special Relativity was introduced and thus, what earlier the theorem would have asserted as mass and energy to be originating from different symmetries then how did we reconcile these two as just one symmetry? How to never "allow this device to access photos and videos"? Horizontal spacing issue in \listoftheorems using amsthm + thmtools Captchas not displaying in SO for me When I get a captcha on Stack Overflow, I don't see the image or the input box with Firefox. I originally had the "HTTPS Anywhere" extension installed but still have the same issue when it's disabled (This caused issues previously when Google's SSL certs were expired for an old domain IIRC).  The requests to Google seem to be never-ending; browsing to the URLs that are still loading results in some pages of JavaScript, but no errors as you'd hope.  The screenshot was taken after the page had been open for more than 3 minutes, and I'm not sure why the GETs are still running. The request popup visible in Firebug is for "GET challenge?k=...."  When browsing to the same captcha page in IE, there are no issues.  I'm aware this could be an issue with my Firefox configuration, as opposed to the site, but would appreciate it if someone could verify if it's just me, and suggest a fix.  EDIT   While visiting the Recaptcha site, I can see a Captcha with no problems If I right-click the problem URLs in FF and Open in new tab, the pages load fine. From the fact that FB omits IP Addresses for the problem ones, I assume that it's not even opening a connection (nor perhaps performing a DNS lookup) Other sites that use Recaptcha seem to work fine (I picked 3 at random from Google) Given two points (defined, for instance using nodes), I want to compute the distance between them.   Is there some build in functionality in tikz to do this? If not, how can it be done using the mathematical engine?   The application I have in mind is to draw an circular arc centered at (a) and passing through some second point (b), where only (a) and (b) are known. Transforming multiple rows into a single row How to delete the files in one folder which are more than 60 days old in UNIX? Proof a $2^n$ by $2^n$ board can be filled using L shaped trominoes and 1 monomino Add review queues to Android app Solve $\lim_{x\to 0} \frac{\sin x-x}{x^3}$ I'm trying to solve this limit     $$\lim_{x\to 0} \frac{\sin x-x}{x^3}$$   Solving using L'hopital rule, we have:  $$\lim_{x\to 0} \frac{\sin x-x}{x^3}= \lim_{x\to 0} \frac{\cos x-1}{3x^2}=\lim_{x\to 0} \frac{-\sin x}{6x}=\lim_{x\to 0} \frac{-\cos x}{6}=-\frac{1}{6}.$$  Am I right?  I'm trying to solve this using change of variables, I need help.  Thanks  EDIT  I didn't understand the answer and the commentaries, I'm looking for an answer using change of variables. Bjarne Stroustrup once mentioned in one of his bigthink interviews that one of the greatest problems most programmers have is not finding or using the right libraries.  On stackoverflow and programmers, I've observed a trend towards questions like "I want to do this, is there a [library | programming language] for that", or "I have these {n} [library | language] candidates for my project; which one would yield me the least amount of headache given these requirements".   Since questions like these aren't exactly programming questions in the sense of "this code should do this, but it does this, why?", they are often (though not always) being closed as "not constructive" because they do not have a definite answer (which is true, and according to the FAQ they would be off-topic on both stackoverflow and programmers).  Nonetheless, I think library questions are valid, and that it is helpful for any programmer to receive independent input from experienced programmers (at least it helps me a lot every time I browse through one of those closed questions, which I found through google). Does anyone agree that posting library choice questions should be explicitly allowed on either stackoverflow or programmers?