+
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Write once, run everywhere+
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==========================+
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  	Good idea, but still wishful thinking.+
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+
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	From my experience I would like to add:+
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        "Write once, run everywhere, show the same behaviour!"	+
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+
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+
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Known bugs and failures:+
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========================+
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+
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- Cut-and-paste+
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	I have not included any code for cut-and-paste. However,+
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	cut-and-paste should work fine under Unix. Cut-and-Paste+
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	also works in MS IE 3.0 under Mickeysoft Windows. For most of +
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        the other platforms (MacOS etc.) and browsers (Netscape etc.)+
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        cut-and-paste does not work.+
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+
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- Security exception+
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	Various versions of Netscape throw a security exception when+
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	I try to suspend the thread of the proof search. I have caught +
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	this exception, but my literature does not tell me how to resume +
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	safely from this exception. In effect the proof search enumerates +
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 	all possible proofs for a sequent and subsequently stops. The user +
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	has no control over how many proofs are shown (the corresponding +
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	windows might appear over each other). This unintended behaviour +
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	has been encountered in:+
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	+
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	  - Netscape Navigator 3.0 Gold under MS Windows'45+
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	  - Netscape Navigator 3.0 under MacOS+
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          - Netscape Communicator 4.0 under MacOS+
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	  - Netscape Navigator 3.01 Gold under Linux+
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	      (But here a "catch" of this exception and a "do nothing" +
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	       helps. God knows why.)+
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	  - possible others+
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+
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- Boxes around the sequents in proofs+
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	I have modified the "Label" class such that the "MyLabel" class +
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	has a surrounding box. This improves the readability of the proofs.+
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	However,  this feature works ONLY under Unix. The boxes do not +
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	appear in MS Windows and MacOS (reason unknown). +
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+
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- Flickering messages+
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	The applet prints some messages ("Grammar error", "No more proofs",+
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	"Not provable", etc.) in a field below the control buttons. +
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	In some browsers the messages only flicker for a short time.+
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	Other browsers show the messages correctly (reason unknown).+
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+
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+
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The applet has been tested under (but see restrictions and bugs):+
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=================================================================+
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+
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Linux:   +
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        Netscape Navigator 3.01 Gold+
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	Netscape Communicator 4.03, 4.04, 4.07 +
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        HotJava 1.1 beta2 (Linux-port)+
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        SUN's appletviewer for JDK 1.1.3+
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        +
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Win'95:+
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        Netscape Navigator 3.0 Gold+
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	Netscape Communicator 4.01a+
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        MS Internet Explorer 3.0.2+
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	MS Internet Explorer 4.0	+
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+
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MacOS:  +
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	Netscape Navigator 3.0+
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	Netscape Communicator 4.0+
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	MS Internet Explorer 3.0.1b1 (PowerPC)+
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+
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+
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Any comments on success or failure for other+
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environments and platforms are appreciated.  +
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+
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Christian.Urban@cl.cam.ac.uk+
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  +
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