Sylladex

The Sylladex is the inventory system in Homestuck. Most player-controlled characters have a Sylladex to store and retrieve artifacts from, which consists of two decks of cards: the Captchalogue Deck and the Strife Deck. These cards have codes on their backs that can be entered on the Punch Designix to create a punched card. The Wayward Vagabond does not possess a sylladex.

Captchalogue Deck
The Captchalogue Deck is where artifacts are stored to be used later. Artifacts are stored on Captchalogue Cards, and while stored, they have no physical size or weight (so while John Egbert is unable to actually use a Sledgehammer on his own, he is still able to carry it around in his Sylladex), making the Sylladex much like a magic satchel. However, there is a limit to how many different items can be captchalogued, based on the number of cards in the character's deck. More cards can be added to the Captchalogue Deck by finding them, captchaloguing them, and then forcing them out of the deck.

Fetch Modi
The fashions in which artifacts are stored to and retrieved from the Sylladex depend on the currently active Fetch Modus. The active Fetch Modus can be chosen as long as the Sylladex has the card with the desired Fetch Modus.

Stack
John's first Sylladex Fetch Modus, signified by a bright magenta Sylladex and matching Captchalogue cards. Captchalogue cards are arranged in a stack, and the player can only use or otherwise interact with the one at the top of the stack. The top card may also be combined with the previous card if doing so is logical (or if the objects can be physically forced into one another), or use it with the previous card. If an object is picked up while the Sylladex is full, the item at the bottom of the stack will be dropped.

Even though his Sylladex is set to Stack by default, John finds his Stack Fetch Modus card under his Magic Chest after He moves it using Sburb.

Queue
The second Fetch Modus John obtains, signified by an orange Sylladex and matching Captchalogue cards. It is essentially the opposite of the Stack, in that only the card at the bottom of the deck (the one that was added before any of the others) may be used directly. It also propels the items that are pushed out of the deck faster (making it a valuable Fetch Modus for weaponizing one's Sylladex). Otherwise, it behaves identically to the Stack.

John finds the Queue Fetch Modus card in a copy of Data Structures for Assholes.

Tree
Rose Lalonde's Fetch Modus, signified by a light green Sylladex and matching Captchalogue cards. She claims that it isn't exactly practical but she thinks it is elegant. The first card is called the Root Card while this Modus is active. Any more items that are picked up are considered Branches. Any cards branching off from Branch cards are called Leaf Cards. If an item is dropped, all items branching off from it will also be dropped. The only card Rose has direct access to is the Root Card, in order to access another object, she must take advantage of the Tree Modus' alphabetical sorting feature which takes action whenever items are acquired, rearranging the order of the items based on the letters that begin their names. Letters coming before the root card becoming branches and leafs to the left side and later letters to the right. The Modus also has an auto-sorting feature if the tree becomes too unbalanced.

Hash Map
Dave Strider's Fetch Modus, signified by a yellow Sylladex and matching Captchalogue cards. Hash maps work through a key-to-value lookup structure, making the Hash Map Fetch Modus the most like a traditional inventory. Each card in the deck is given an index from zero to the number of cards in the deck minus 1 (10 cards leaves an index range of 0 to 9). When an item is captchalogued into a Hash Map Sylladex, where it is placed into the card stack depending on the current Hash Function. If an object already occupies the card with the produced index, the item in the card is ejected from the Sylladex to make room for the new item. In order to retrieve an item from the stack, the character must perform an action related to the item with a keyword that will produce the same index as the card that holds the desired item. Items apparently are retrieved so long as a relevant command with an equivalent hash is uttered, regardless of Dave's actual desire to use the item. If the objects are retrieved this way, then they're thrown out as if another item was placed in their card. The force of which the item ejects from the Sylladex may be relevant to how much emphasis is used on the command.

On the back of the fetch modus card are several options. One of them, a "potentially dangerous button," ejects every item in the Sylladex. Another option allows the user to change the hash function used to calculate indexes, though changing the hash function will eject all items too. A final option is a check box labelled 'detect collisions' which originally was unchecked. Now that it's checked, Dave is prevented from captchaloging an item when doing so will cause another item to be displaced and ejected, making captchaloging slower but safer.

It is notable that objects that are captchalogued don't have a set name. For example, Dave captchalogued multiple Shuriken (3) one at a time to avoid dislodging a Box (5) he had filled with Fireworks (5). This is after he spilled the Box of Fireworks (3) by replacing it with Nunchaku (3). Items that share the same index can be combined even if the combined name of the items wouldn't equal that index.

Hash Functions

 * The hash function Dave uses most often gives each letter in the word of an item's name a value (2 for consonants and 1 for vowels), adds the numbers up, and divides the sum by the number of Captchalogue Cards in the deck. The index is the remainder. The letter "Y" can be used as either a constant or a vowel, but only a hashmap noob would use such a cheap trick.
 * Another hash function switches the values, making vowels worth 2 and consonants worth 1.
 * A third function gives every letter the same value the letter would have in a game of Scrabble. Specifically, A=1, B=3, C=3, D=2, E=1, F=4, G=2, H=4, I=1, J=8, K=5, L=1, M=3, N=1, O=1, P=3, Q=10, R=1, S=1, T=1, U=1, V=4, W=4, X=8, Y=4, and Z=10.

Strife Deck
Items can also be placed into a Strife Deck, which allows the player to use objects to Aggrieve enemies. Each Strife Deck is contained with a Strife Specibus and a character with multiple Strife Specibi will store them within a Strife Portfolio. In order for an artifact to be allocated to a Strife Deck, it must be the same kind of item as the character's chosen Kind Abstratus, and there must be a free Captchalogue Card in the Strife Deck.

It should be noted that imps can also place items into their strife deck. They drop their Strife Specibi card when defeated.


 * John's is hammerKind, originally holding both a hammer and a sledgehammer. However, the sledgehammer lost its metal head while he was using it, changing the Specibus' Kind Abstratus into a handleKind and ejecting the other hammer's head. When John repaired the sledgehammer hammerKind restored itself and he lost the rest of the hammer. John also acquired a bunnyKind Specibus and deck from a Shale Imp.
 * Rose's is needleKind and holds her knitting needles
 * Dave's is bladeKind and would hold his first ninja sword, but he accidentally launched it out of his window at a rambunctious crow and now holds a 2nd ninja sword from his wall.
 * gardenGnostic's is unknown so far.

Apparently, artifacts allocated to the Strife Deck can be used at will.