Instructions for Running SHRDLU SHRDLU can be in 4 basic states, COMMAND, READY, RUN, and REQUEST. It is initially in READY when loaded. *** ******COMMAND STATE *** In this state, SHRDLU expects the user to type a command. It lets you know this by typing ">>>". A command is a line containing one or more words, separated by spaces and terminated by two carriage returns (). The first word must be one of the three words SHOW, TELL, or GO. The SHOW command is used to ask the system to show such things as definitions, structures it is building, and the states of various parameters and switches. TELL is used to tell the system new definitions and settings. After executing a COMMAND, the system is ready for another one, and prompts by saying >>>. You can leave COMMAND state by typing T,NIL, or $P (-P) instead of a command. This will cause the program to continue whatever it was doing before it entered COMMAND state, or to go to READY state if it was not already in the process of analyzing a sentence. If instead, you type the command "GO", it will drop the sentence it is working on, and go into READY state for a new one. Of course, the COMMAND state is just a slightly-fudged LISP listen loop, so you can type any atom or S-expression at it to be evaluted, go from it into the LISP editor, define new functions,etc. **** ******COMMAND FORMATS **** The SHOW and TELL commands are based on trees (one tree for each). The first word of the command is SHOW or TELL, the second names a node in the corresponding tree, and the rest are any arguments appropriate to the action at that node. For example, the command: SHOW FUNCTION MEET will display the contents of the LISP function "MEET". SHOW SHOW displays the "SHOW" tree, while for the "TELL" tree, you type SHOW TELL If all of the arguments are not specified, the system will request more. For example, typing: SHOW FUNCTION would cause it to type out: FUNCTION: requesting the name of a function from the user. It is then in REQUEST state (see below.) Non-terminal nodes of the tree may or may not have corresponding actions. For example, the command TELL PLANNER OFF causes the entire batch of PLANNER tracing devices to be turned off at once, even though there are subnodes of the PLANNER node which can be used to turn individual features on and off selectively. If there is no action associated with such a node, the system will ask the user to select one of its subnodes. If you type "SHOW" or "TELL" followed by two carriage return, it will guide you through the choices, using REQUESTS (see below). Typing HELP will allow you to see this message or a shorter version which contains just the most salient details of the four states. ***** *****REQUEST STATE ***** SHRDLU can request two kinds of information from the user. If it wants him to CHOOSE between a set of alternatives, it will end the request with a ?. If it wants him to SPECIFY a name or list of names, it will end it with a :. For a CHOOSE, all it needs is enough information to decide between the alternatives. Begin typing your choice, and when it is complete enough, type a . If you type fewer letters than necessary (e.g. typing just a P, when PLANNER and PARSING are among the choices) it will do nothing and wait for you to continue. If you type more than necessary it doesn't matter. For a SPECIFY, type the required response, terminated by a . If you type a with nothing else, it will take some default response which is appropriate to the action (For example, typing a in response to a request for which properties of an atomare to be displayed will have the effect of displaying all of them. For either SPECIFY or CHOOSE, you can get more information on what is expected by typing a ?. It will then give you the request again. Typing QUIT at a "SPECIFY" REQUEST or QUIT at a "CHOOSE" REQUEST will cause the entire command of which it was a part to be discarded without finishing, returning to COMMAND state. ***** ******READY STATE ***** The READY state is entered only when a new English sentence is to be input. You can tell you are in it when the sytem types READY Respond by typing in an English sentence in normal punctuation (i.e. ending with a question mark or period). The system will automatically begin processing it, entering RUN state. To get into a COMMAND state while entering a sentence, type . ***** ******RUN STATE ***** Whenever a sentence is input, the system begins to RUN. It will stop at selected places, entering COMMAND state so the user can SHOW things and TELL it things before continuing. There are various TELL commands which explain how to change these stopping points. When a T,NIL, or -P is typed at the COMMAND state, the system returns to RUN and continues. ***** Any word which appears in the SHOW or TELL trees can be abbreviated by typing its first two letters. For example, our first command above could have been abbreviated as: SH FU MEET Note that arguments cannot be abbreviated since the system has no list to check the abbreviations against. This is also true of responses to a "SPECIFY" REQUEST. Responses to a "CHOOSE" REQUEST are abbreviated by typing any initial letter string followed by as described above. ***** ***** @